WorldWideScience

Sample records for vascular network formation

  1. Vascular pattern formation in plants.

    Science.gov (United States)

    Scarpella, Enrico; Helariutta, Ykä

    2010-01-01

    Reticulate tissue systems exist in most multicellular organisms, and the principles underlying the formation of cellular networks have fascinated philosophers, mathematicians, and biologists for centuries. In particular, the beautiful and varied arrangements of vascular tissues in plants have intrigued mankind since antiquity, yet the organizing signals have remained elusive. Plant vascular tissues form systems of interconnected cell files throughout the plant body. Vascular cells are aligned with one another along continuous lines, and vascular tissues differentiate at reproducible positions within organ environments. However, neither the precise path of vascular differentiation nor the exact geometry of vascular networks is fixed or immutable. Several recent advances converge to reconcile the seemingly conflicting predictability and plasticity of vascular tissue patterns. A control mechanism in which an apical-basal flow of signal establishes a basic coordinate system for body axis formation and vascular strand differentiation, and in which a superimposed level of radial organizing cues elaborates cell patterns, would generate a reproducible tissue configuration in the context of an underlying robust, self-organizing structure, and account for the simultaneous regularity and flexibility of vascular tissue patterns. Copyright 2010 Elsevier Inc. All rights reserved.

  2. Vascular lumen formation.

    Science.gov (United States)

    Lammert, Eckhard; Axnick, Jennifer

    2012-04-01

    The vascular system developed early in evolution. It is required in large multicellular organisms for the transport of nutrients, oxygen, and waste products to and from tissues. The vascular system is composed of hollow tubes, which have a high level of complexity in vertebrates. Vasculogenesis describes the de novo formation of blood vessels, e.g., aorta formation in vertebrate embryogenesis. In contrast, angiogenesis is the formation of blood vessels from preexisting ones, e.g., sprouting of intersomitic blood vessels from the aorta. Importantly, the lumen of all blood vessels in vertebrates is lined and formed by endothelial cells. In both vasculogenesis and angiogenesis, lumen formation takes place in a cord of endothelial cells. It involves a complex molecular mechanism composed of endothelial cell repulsion at the cell-cell contacts within the endothelial cell cords, junctional rearrangement, and endothelial cell shape change. As the vascular system also participates in the course of many diseases, such as cancer, stroke, and myocardial infarction, it is important to understand and make use of the molecular mechanisms of blood vessel formation to better understand and manipulate the pathomechanisms involved.

  3. A review of mathematical models for the formation of vascular networks

    KAUST Repository

    Scianna, M.

    2013-09-01

    Two major mechanisms are involved in the formation of blood vasculature: vasculogenesis and angiogenesis. The former term describes the formation of a capillary-like network from either a dispersed or a monolayered population of endothelial cells, reproducible also in vitro by specific experimental assays. The latter term describes the sprouting of new vessels from an existing capillary or post-capillary venule. Similar mechanisms are also involved in the formation of the lymphatic system through a process generally called lymphangiogenesis. A number of mathematical approaches have been used to analyze these phenomena. In this paper, we review the different types of models, with special emphasis on their ability to reproduce different biological systems and to predict measurable quantities which describe the overall processes. Finally, we highlight the advantages specific to each of the different modelling approaches. © 2013 Elsevier Ltd.

  4. Dynamics of nephron-vascular network

    DEFF Research Database (Denmark)

    Postnov, Dmitry; Postnov, D E; Marsh, D J

    2012-01-01

    The paper presents a modeling study of the spatial dynamics of a nephro-vascular network consisting of individual nephrons connected via a tree-like vascular branching structure. We focus on the effects of nonlinear mechanisms that are responsible for the formation of synchronous patterns in order...

  5. Laminin promotes vascular network formation in 3D in vitro collagen scaffolds by regulating VEGF uptake.

    Science.gov (United States)

    Stamati, Katerina; Priestley, John V; Mudera, Vivek; Cheema, Umber

    2014-09-10

    Angiogenesis is an essential neovascularisation process, which if recapitulated in 3D in vitro, will provide better understanding of endothelial cell (EC) behaviour. Various cell types and growth factors are involved, with vascular endothelial growth factor (VEGF) and its receptors VEGFR1 and VEGFR2 key components. We were able to control the aggregation pattern of ECs in 3D collagen hydrogels, by varying the matrix composition and/or having a source of cells signalling angiogenic proteins. These aggregation patterns reflect the different developmental pathways that ECs take to form different sized tubular structures. Cultures with added laminin and thus increased expression of α6 integrin showed a significant increase (p3D. Copyright © 2014 The Authors. Published by Elsevier Inc. All rights reserved.

  6. Neuroblast survival depends on mature vascular network formation after mouse stroke: role of endothelial and smooth muscle progenitor cell co-administration.

    Science.gov (United States)

    Nih, Lina R; Deroide, Nicolas; Leré-Déan, Carole; Lerouet, Dominique; Soustrat, Mathieu; Levy, Bernard I; Silvestre, Jean-Sébastien; Merkulova-Rainon, Tatiana; Pocard, Marc; Margaill, Isabelle; Kubis, Nathalie

    2012-04-01

    Pro-angiogenic cell-based therapies constitute an interesting and attractive approach to enhancing post-stroke neurogenesis and decreasing neurological deficit. However, most new stroke-induced neurons die during the first few weeks after ischemia, thus impairing total recovery. Although the neovascularization process involves different cell types and various growth factors, most cell therapy protocols are based on the biological effects of single-cell-type populations or on the administration of heterogeneous populations of progenitors, namely human cord blood-derived CD34(+) cells, with scarce vascular progenitor cells. Tight cooperation between endothelial cells and smooth muscle cells/pericytes is critical for the development of functional neovessels. We hypothesized that neuroblast survival in stroke brain depends on mature vascular network formation. In this study, we injected a combination of endothelial progenitor cells (EPCs) and smooth muscle progenitor cells (SMPCs), isolated from human umbilical cord blood, into a murine model of permanent focal ischemia induced by middle cerebral artery occlusion. The co-administration of SMPCs and EPCs induced enhanced angiogenesis and vascular remodeling in the peri-infarct and infarct areas, where vessels exhibited a more mature phenotype. This activation of vessel growth resulted in the maintenance of neurogenesis and neuroblast migration to the peri-ischemic cortex. Our data suggest that a mature vascular network is essential for neuroblast survival after cerebral ischemia, and that co-administration of EPCs and SMPCs may constitute a novel therapeutic strategy for improving the treatment of stroke. © 2012 The Authors. European Journal of Neuroscience © 2012 Federation of European Neuroscience Societies and Blackwell Publishing Ltd.

  7. Formation of multiple networks

    DEFF Research Database (Denmark)

    Magnani, Matteo; Rossi, Luca

    2013-01-01

    we introduce the first network formation model for multiple networks. Network formation models are among the most popular tools in traditional network studies, because of both their practical and theoretical impact. However, existing models are not sufficient to describe the generation of multiple...

  8. Graph analysis of cell clusters forming vascular networks

    Science.gov (United States)

    Alves, A. P.; Mesquita, O. N.; Gómez-Gardeñes, J.; Agero, U.

    2018-03-01

    This manuscript describes the experimental observation of vasculogenesis in chick embryos by means of network analysis. The formation of the vascular network was observed in the area opaca of embryos from 40 to 55 h of development. In the area opaca endothelial cell clusters self-organize as a primitive and approximately regular network of capillaries. The process was observed by bright-field microscopy in control embryos and in embryos treated with Bevacizumab (Avastin), an antibody that inhibits the signalling of the vascular endothelial growth factor (VEGF). The sequence of images of the vascular growth were thresholded, and used to quantify the forming network in control and Avastin-treated embryos. This characterization is made by measuring vessels density, number of cell clusters and the largest cluster density. From the original images, the topology of the vascular network was extracted and characterized by means of the usual network metrics such as: the degree distribution, average clustering coefficient, average short path length and assortativity, among others. This analysis allows to monitor how the largest connected cluster of the vascular network evolves in time and provides with quantitative evidence of the disruptive effects that Avastin has on the tree structure of vascular networks.

  9. Multinephron dynamics on the renal vascular network

    DEFF Research Database (Denmark)

    Marsh, Donald J; Wexler, Anthony S; Brazhe, Alexey

    2012-01-01

    Tubuloglomerular feedback (TGF) and the myogenic mechanism combine in each nephron to regulate blood flow and glomerular filtration rate. Both mechanisms are non-linear, generate self-sustained oscillations, and interact as their signals converge on arteriolar smooth muscle, forming a regulatory...... clusters. In-phase synchronization predominated among nephrons separated by 1 or 3 vascular nodes, and anti-phase synchronization for 5 or 7 nodes of separation. Nephron dynamics were irregular and contained low frequency fluctuations. Results are consistent with simultaneous blood flow measurements...... of both mechanisms in the regulatory ensemble, to examine the effects of network structure on nephron synchronization. Symmetry, as a property of a network, facilitates synchronization. Nephrons received blood from a symmetric electrically conductive vascular tree. Symmetry was created by using identical...

  10. Coevolutionary modeling in network formation

    KAUST Repository

    Al-Shyoukh, Ibrahim

    2014-12-03

    Network coevolution, the process of network topology evolution in feedback with dynamical processes over the network nodes, is a common feature of many engineered and natural networks. In such settings, the change in network topology occurs at a comparable time scale to nodal dynamics. Coevolutionary modeling offers the possibility to better understand how and why network structures emerge. For example, social networks can exhibit a variety of structures, ranging from almost uniform to scale-free degree distributions. While current models of network formation can reproduce these structures, coevolutionary modeling can offer a better understanding of the underlying dynamics. This paper presents an overview of recent work on coevolutionary models of network formation, with an emphasis on the following three settings: (i) dynamic flow of benefits and costs, (ii) transient link establishment costs, and (iii) latent preferential attachment.

  11. Coevolutionary modeling in network formation

    KAUST Repository

    Al-Shyoukh, Ibrahim; Chasparis, Georgios; Shamma, Jeff S.

    2014-01-01

    Network coevolution, the process of network topology evolution in feedback with dynamical processes over the network nodes, is a common feature of many engineered and natural networks. In such settings, the change in network topology occurs at a comparable time scale to nodal dynamics. Coevolutionary modeling offers the possibility to better understand how and why network structures emerge. For example, social networks can exhibit a variety of structures, ranging from almost uniform to scale-free degree distributions. While current models of network formation can reproduce these structures, coevolutionary modeling can offer a better understanding of the underlying dynamics. This paper presents an overview of recent work on coevolutionary models of network formation, with an emphasis on the following three settings: (i) dynamic flow of benefits and costs, (ii) transient link establishment costs, and (iii) latent preferential attachment.

  12. Cues for cellular assembly of vascular elastin networks

    Science.gov (United States)

    Kothapalli, Chandrasekhar R.

    LOX protein synthesis (2.5-fold); these cues also enhanced deposition of mature elastic fibers (˜1 mum diameter) within these cultures. Interestingly, instead of copper salt addition, even release of Cu 2+ ions (˜0.1 M) from copper nanoparticles (400 ng/mL), concurrent with HA oligomers, promoted crosslinking of elastin into mature matrix, with multiple bundles of highly-crosslinked elastin fiber formation observed (diameter ˜200-500 nm). These results strongly attest to the potential individual and combined benefits of these cues to faithful elastin matrix regeneration by healthy, patient-derived cells within tissue-engineered vascular constructs. When these cues (TGF-beta1 and HA oligomers) were added to TNF-alpha-stimulated SMC cultures, model cell culture systems mimicking phenotypically-altered cells within aneurysms, they upregulated elastin matrix production, organized elastin protein into fibers, and simultaneously stabilized this matrix by attenuating production of elastolytic enzymes. Similarly these cues also attenuated inflammatory cytokines release within cells isolated from induced-aortic aneurysms in rats, and significantly upregulated elastin synthesis and matrix formation by upregulating LOX and desmosine protein amounts. The cues were also highly effective in organizing the elastin into fibrous matrix structures mimicking the native elastin deposition process. The outcomes of this study might be of tremendous use in optimizing design of HA constructs to modulate vascular healing and matrix synthesis following revascularization, and in enabling repair of elastin networks within diseased or inflammatory (aneurysmal) adult vascular tissues.

  13. Cell proliferation along vascular islands during microvascular network growth

    Directory of Open Access Journals (Sweden)

    Kelly-Goss Molly R

    2012-06-01

    Full Text Available Abstract Background Observations in our laboratory provide evidence of vascular islands, defined as disconnected endothelial cell segments, in the adult microcirculation. The objective of this study was to determine if vascular islands are involved in angiogenesis during microvascular network growth. Results Mesenteric tissues, which allow visualization of entire microvascular networks at a single cell level, were harvested from unstimulated adult male Wistar rats and Wistar rats 3 and 10 days post angiogenesis stimulation by mast cell degranulation with compound 48/80. Tissues were immunolabeled for PECAM and BRDU. Identification of vessel lumens via injection of FITC-dextran confirmed that endothelial cell segments were disconnected from nearby patent networks. Stimulated networks displayed increases in vascular area, length density, and capillary sprouting. On day 3, the percentage of islands with at least one BRDU-positive cell increased compared to the unstimulated level and was equal to the percentage of capillary sprouts with at least one BRDU-positive cell. At day 10, the number of vascular islands per vascular area dramatically decreased compared to unstimulated and day 3 levels. Conclusions These results show that vascular islands have the ability to proliferate and suggest that they are able to incorporate into the microcirculation during the initial stages of microvascular network growth.

  14. Stages of neuronal network formation

    International Nuclear Information System (INIS)

    Woiterski, Lydia; Käs, Josef A; Claudepierre, Thomas; Luxenhofer, Robert; Jordan, Rainer

    2013-01-01

    Graph theoretical approaches have become a powerful tool for investigating the architecture and dynamics of complex networks. The topology of network graphs revealed small-world properties for very different real systems among these neuronal networks. In this study, we observed the early development of mouse retinal ganglion cell (RGC) networks in vitro using time-lapse video microscopy. By means of a time-resolved graph theoretical analysis of the connectivity, shortest path length and the edge length, we were able to discover the different stages during the network formation. Starting from single cells, at the first stage neurons connected to each other ending up in a network with maximum complexity. In the further course, we observed a simplification of the network which manifested in a change of relevant network parameters such as the minimization of the path length. Moreover, we found that RGC networks self-organized as small-world networks at both stages; however, the optimization occurred only in the second stage. (paper)

  15. Network Formation under the Threat of Disruption

    NARCIS (Netherlands)

    Hoyer, B.

    2013-01-01

    The studies in this thesis are focused on the impact the presence of a network disruptor has on network formation models. In particular, we build two theoretical models to study the effect of network disruption on network formation and test the effect network disruption has on equilibrium selection

  16. Vascular Endothelial Growth Factor Sequestration Enhances In Vivo Cartilage Formation

    Directory of Open Access Journals (Sweden)

    Carolina M. Medeiros Da Cunha

    2017-11-01

    Full Text Available Autologous chondrocyte transplantation for cartilage repair still has unsatisfactory clinical outcomes because of inter-donor variability and poor cartilage quality formation. Re-differentiation of monolayer-expanded human chondrocytes is not easy in the absence of potent morphogens. The Vascular Endothelial Growth Factor (VEGF plays a master role in angiogenesis and in negatively regulating cartilage growth by stimulating vascular invasion and ossification. Therefore, we hypothesized that its sole microenvironmental blockade by either VEGF sequestration by soluble VEGF receptor-2 (Flk-1 or by antiangiogenic hyperbranched peptides could improve chondrogenesis of expanded human nasal chondrocytes (NC freshly seeded on collagen scaffolds. Chondrogenesis of several NC donors was assessed either in vitro or ectopically in nude mice. VEGF blockade appeared not to affect NC in vitro differentiation, whereas it efficiently inhibited blood vessel ingrowth in vivo. After 8 weeks, in vivo glycosaminoglycan deposition was approximately two-fold higher when antiangiogenic approaches were used, as compared to the control group. Our data indicates that the inhibition of VEGF signaling, independently of the specific implementation mode, has profound effects on in vivo NC chondrogenesis, even in the absence of chondroinductive signals during prior culture or at the implantation site.

  17. Experimental study upon the effect of irradiation on callus formation of fracture. Observation of vascular alteration and callus formation

    Energy Technology Data Exchange (ETDEWEB)

    Saigusa, F [Nippon Dental Coll., Tokyo

    1981-02-01

    Irradiation effects on callus formation after bone fracture were studied in rats with fractured right lower extremity. Follow-up study was continued for 112 days since 3000 rad was irradiated to the fractured site 3 days after bone fracture. Callus formation was noted in both of the outer and inner part (bone marrow) of the diaphysis before 14 days after bone fracture, but it was slow and sparse compared with that of non-irradiated group. Callus formation tended to disappear gradually from the outside of the diaphysis after 28 days after bone fracture. Strong disturbance was found in the surrounding vascular system at this time. Inside of the diaphysis, callus formation was restricted the end of the fracture, where lamellar calluses fused together. Changes in vascular system remained until 56 days after bone fracture. Vascular distribution was most dense 28 days after bone fracture. In many of the calluses which have established fusion, findings suggested excessive calcification in the trabeculae. Vascular distribution at this time was sparse, vascular formation was markedly suppressed in the bone marrow, and very little vascular formation was found in the fractured edges of the bone.

  18. Vascular dynamics aid a coupled neurovascular network learn sparse independent features: A computational model

    Directory of Open Access Journals (Sweden)

    Ryan Thomas Philips

    2016-02-01

    Full Text Available Cerebral vascular dynamics are generally thought to be controlled by neural activity in a unidirectional fashion. However, both computational modeling and experimental evidence point to the feedback effects of vascular dynamics on neural activity. Vascular feedback in the form of glucose and oxygen controls neuronal ATP, either directly or via the agency of astrocytes, which in turn modulates neural firing. Recently, a detailed model of the neuron-astrocyte-vessel system has shown how vasomotion can modulate neural firing. Similarly, arguing from known cerebrovascular physiology, an approach known as `hemoneural hypothesis' postulates functional modulation of neural activity by vascular feedback. To instantiate this perspective, we present a computational model in which a network of `vascular units' supplies energy to a neural network. The complex dynamics of the vascular network, modeled by a network of oscillators, turns neurons ON and OFF randomly. The informational consequence of such dynamics is explored in the context of an auto-encoder network. In the proposed model, each vascular unit supplies energy to a subset of hidden neurons of an autoencoder network, which constitutes its `projective field'. Neurons that receive adequate energy in a given trial have reduced threshold, and thus are prone to fire. Dynamics of the vascular network are governed by changes in the reconstruction error of the auto-encoder network, interpreted as the neuronal demand. Vascular feedback causes random inactivation of a subset of hidden neurons in every trial. We observe that, under conditions of desynchronized vascular dynamics, the output reconstruction error is low and the feature vectors learnt are sparse and independent. Our earlier modeling study highlighted the link between desynchronized vascular dynamics and efficient energy delivery in skeletal muscle. We now show that desynchronized vascular dynamics leads to efficient training in an auto

  19. Continuum Modeling of Biological Network Formation

    KAUST Repository

    Albi, Giacomo; Burger, Martin; Haskovec, Jan; Markowich, Peter A.; Schlottbom, Matthias

    2017-01-01

    We present an overview of recent analytical and numerical results for the elliptic–parabolic system of partial differential equations proposed by Hu and Cai, which models the formation of biological transportation networks. The model describes

  20. Insulin resistance in vascular endothelial cells promotes intestinal tumour formation

    DEFF Research Database (Denmark)

    Wang, X; Häring, M-F; Rathjen, Thomas

    2017-01-01

    in vascular endothelial cells. Strikingly, these mice had 42% more intestinal tumours than controls, no change in tumour angiogenesis, but increased expression of vascular cell adhesion molecule-1 (VCAM-1) in primary culture of tumour endothelial cells. Insulin decreased VCAM-1 expression and leukocyte...... adhesion in quiescent tumour endothelial cells with intact insulin receptors and partly prevented increases in VCAM-1 and leukocyte adhesion after treatment with tumour necrosis factor-α. Knockout of insulin receptors in endothelial cells also increased leukocyte adhesion in mesenteric venules...

  1. Directed networks, allocation properties and hierarchy formation

    NARCIS (Netherlands)

    Slikker, M.; Gilles, R.P.; Norde, H.W.; Tijs, S.H.

    2005-01-01

    We investigate properties for allocation rules on directed communication networks and the formation of such networks under these payoff properties. We study allocation rules satisfying two appealing properties, Component Efficiency (CE) and the Hierarchical Payoff Property (HPP). We show that such

  2. Limited farsightedness in network formation

    NARCIS (Netherlands)

    Morbitzer, D.T.

    2013-01-01

    Social relationships can be beneficial for various reasons. For example, people find jobs through their social contacts, and researchers connect with each other to cooperate on projects. Within these networks of relations, actors maintain different positions, which can influence their outcomes.

  3. Network Configuration Analysis for Formation Flying Satellites

    Science.gov (United States)

    Knoblock, Eric J.; Wallett, Thomas M.; Konangi, Vijay K.; Bhasin, Kul B.

    2001-01-01

    The performance of two networks to support autonomous multi-spacecraft formation flying systems is presented. Both systems are comprised of a ten-satellite formation, with one of the satellites designated as the central or 'mother ship.' All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/EP over ATM protocol architecture within the formation, and the second system uses the IEEE 802.11 protocol architecture within the formation. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IP queuing delay, IP queue size and IP processing delay at the mother ship as well as end-to-end delay for both systems. In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  4. Consensus formation on coevolving networks: groups' formation and structure

    International Nuclear Information System (INIS)

    Kozma, Balazs; Barrat, Alain

    2008-01-01

    We study the effect of adaptivity on a social model of opinion dynamics and consensus formation. We analyse how the adaptivity of the network of contacts between agents to the underlying social dynamics affects the size and topological properties of groups and the convergence time to the stable final state. We find that, while on static networks these properties are determined by percolation phenomena, on adaptive networks the rewiring process leads to different behaviors: adaptive rewiring fosters group formation by enhancing communication between agents of similar opinion, though it also makes possible the division of clusters. We show how the convergence time is determined by the characteristic time of link rearrangement. We finally investigate how the adaptivity yields nontrivial correlations between the internal topology and the size of the groups of agreeing agents

  5. Investigating water transport through the xylem network in vascular plants.

    Science.gov (United States)

    Kim, Hae Koo; Park, Joonghyuk; Hwang, Ildoo

    2014-04-01

    Our understanding of physical and physiological mechanisms depends on the development of advanced technologies and tools to prove or re-evaluate established theories, and test new hypotheses. Water flow in land plants is a fascinating phenomenon, a vital component of the water cycle, and essential for life on Earth. The cohesion-tension theory (CTT), formulated more than a century ago and based on the physical properties of water, laid the foundation for our understanding of water transport in vascular plants. Numerous experimental tools have since been developed to evaluate various aspects of the CTT, such as the existence of negative hydrostatic pressure. This review focuses on the evolution of the experimental methods used to study water transport in plants, and summarizes the different ways to investigate the diversity of the xylem network structure and sap flow dynamics in various species. As water transport is documented at different scales, from the level of single conduits to entire plants, it is critical that new results be subjected to systematic cross-validation and that findings based on different organs be integrated at the whole-plant level. We also discuss the functional trade-offs between optimizing hydraulic efficiency and maintaining the safety of the entire transport system. Furthermore, we evaluate future directions in sap flow research and highlight the importance of integrating the combined effects of various levels of hydraulic regulation.

  6. Protocol for Communication Networking for Formation Flying

    Science.gov (United States)

    Jennings, Esther; Okino, Clayton; Gao, Jay; Clare, Loren

    2009-01-01

    An application-layer protocol and a network architecture have been proposed for data communications among multiple autonomous spacecraft that are required to fly in a precise formation in order to perform scientific observations. The protocol could also be applied to other autonomous vehicles operating in formation, including robotic aircraft, robotic land vehicles, and robotic underwater vehicles. A group of spacecraft or other vehicles to which the protocol applies could be characterized as a precision-formation- flying (PFF) network, and each vehicle could be characterized as a node in the PFF network. In order to support precise formation flying, it would be necessary to establish a corresponding communication network, through which the vehicles could exchange position and orientation data and formation-control commands. The communication network must enable communication during early phases of a mission, when little positional knowledge is available. Particularly during early mission phases, the distances among vehicles may be so large that communication could be achieved only by relaying across multiple links. The large distances and need for omnidirectional coverage would limit communication links to operation at low bandwidth during these mission phases. Once the vehicles were in formation and distances were shorter, the communication network would be required to provide high-bandwidth, low-jitter service to support tight formation-control loops. The proposed protocol and architecture, intended to satisfy the aforementioned and other requirements, are based on a standard layered-reference-model concept. The proposed application protocol would be used in conjunction with conventional network, data-link, and physical-layer protocols. The proposed protocol includes the ubiquitous Institute of Electrical and Electronics Engineers (IEEE) 802.11 medium access control (MAC) protocol to be used in the datalink layer. In addition to its widespread and proven use in

  7. STEREOLOGICAL ANALYSIS OF THE HUMAN PONS VASCULAR NETWORK

    Directory of Open Access Journals (Sweden)

    Ivan Jovanović

    2003-04-01

    Full Text Available Liver is the largest parenchymatous organ, well vascularized, weighing approximately 1.8-3.0% of the whole body weight. Among all abdominal traumas liver injuries account for 25%. For more serious liver injuries the mortality is around 40% in children below 10 years of age. For lesions of the juxtahepatic veins (three major hepatic veins or the retrohepatic portion of v. cava or for complex, combined intra abdominal injuries, the mortality is even up to 70%.This work analyzed the period 1988-2000 during which there were 19 children admitted and treated for blunt liver injuries at the Clinic of Pediatric Surgery and Orthopedics in Nis; I, II and III scale injuries prevailed (17 cases; 89.4%. These injuries were surgically treated for the most part (17 cases; 89.4%. In 7 children (36.8% there were combined injuries. The lethality was 26.3%-5 cases, with three major complications: two intrahepatic hematomas and one biliary fistula associated with biliary peritonitis and biloma formation.

  8. Networks for Autonomous Formation Flying Satellite Systems

    Science.gov (United States)

    Knoblock, Eric J.; Konangi, Vijay K.; Wallett, Thomas M.; Bhasin, Kul B.

    2001-01-01

    The performance of three communications networks to support autonomous multi-spacecraft formation flying systems is presented. All systems are comprised of a ten-satellite formation arranged in a star topology, with one of the satellites designated as the central or "mother ship." All data is routed through the mother ship to the terrestrial network. The first system uses a TCP/lP over ATM protocol architecture within the formation the second system uses the IEEE 802.11 protocol architecture within the formation and the last system uses both of the previous architectures with a constellation of geosynchronous satellites serving as an intermediate point-of-contact between the formation and the terrestrial network. The simulations consist of file transfers using either the File Transfer Protocol (FTP) or the Simple Automatic File Exchange (SAFE) Protocol. The results compare the IF queuing delay, and IP processing delay at the mother ship as well as application-level round-trip time for both systems, In all cases, using IEEE 802.11 within the formation yields less delay. Also, the throughput exhibited by SAFE is better than FTP.

  9. Continuum Modeling of Biological Network Formation

    KAUST Repository

    Albi, Giacomo

    2017-04-10

    We present an overview of recent analytical and numerical results for the elliptic–parabolic system of partial differential equations proposed by Hu and Cai, which models the formation of biological transportation networks. The model describes the pressure field using a Darcy type equation and the dynamics of the conductance network under pressure force effects. Randomness in the material structure is represented by a linear diffusion term and conductance relaxation by an algebraic decay term. We first introduce micro- and mesoscopic models and show how they are connected to the macroscopic PDE system. Then, we provide an overview of analytical results for the PDE model, focusing mainly on the existence of weak and mild solutions and analysis of the steady states. The analytical part is complemented by extensive numerical simulations. We propose a discretization based on finite elements and study the qualitative properties of network structures for various parameter values.

  10. Indian-ink perfusion based method for reconstructing continuous vascular networks in whole mouse brain.

    Directory of Open Access Journals (Sweden)

    Songchao Xue

    Full Text Available The topology of the cerebral vasculature, which is the energy transport corridor of the brain, can be used to study cerebral circulatory pathways. Limited by the restrictions of the vascular markers and imaging methods, studies on cerebral vascular structure now mainly focus on either observation of the macro vessels in a whole brain or imaging of the micro vessels in a small region. Simultaneous vascular studies of arteries, veins and capillaries have not been achieved in the whole brain of mammals. Here, we have combined the improved gelatin-Indian ink vessel perfusion process with Micro-Optical Sectioning Tomography for imaging the vessel network of an entire mouse brain. With 17 days of work, an integral dataset for the entire cerebral vessels was acquired. The voxel resolution is 0.35×0.4×2.0 µm(3 for the whole brain. Besides the observations of fine and complex vascular networks in the reconstructed slices and entire brain views, a representative continuous vascular tracking has been demonstrated in the deep thalamus. This study provided an effective method for studying the entire macro and micro vascular networks of mouse brain simultaneously.

  11. Photoacoustic imaging of vascular networks in transgenic mice

    Science.gov (United States)

    Laufer, J. G.; Cleary, J. O.; Zhang, E. Z.; Lythgoe, M. F.; Beard, P. C.

    2010-02-01

    The preferential absorption of near infrared light by blood makes photoacoustic imaging well suited to visualising vascular structures in soft tissue. In addition, the spectroscopic specificity of tissue chromophores can be exploited by acquiring images at multiple excitation wavelengths. This allows the quantification of endogenous chromophores, such as oxy- and deoxyhaemoglobin, and hence blood oxygenation, and the detection of exogenous chromophores, such as functionalised contrast agents. More importantly, this approach has the potential to visualise the spatial distribution of low concentrations of functionalised contrast agents against the strong background absorption of the endogenous chromophores. This has a large number of applications in the life sciences. One example is the structural and functional phenotyping of transgenic mice for the study of the genetic origins of vascular malformations, such as heart defects. In this study, photoacoustic images of mouse embryos have been acquired to study the development of the vasculature following specific genetic knockouts.

  12. Functional organization of the vascular network of Physarum polycephalum

    International Nuclear Information System (INIS)

    Baumgarten, Werner; Hauser, Marcus J B

    2013-01-01

    The plasmodium of the slime mould Physarum polycephalum forms a transportation network of veins, in which protoplasm is transported due to peristaltic pumping. This network forms a planar, weighted, undirected graph that, for the first time, can be extracted automatically from photographs or movies. Thus, data from real transportation networks have now become available for the investigation of network properties. We determine the local drag of the vein segments and use these data to calculate the transport efficiency. We unravel which veins form the backbone of the transportation network by using a centrality measure from graph theory. The principal vein segments lie on relatively ample cycles of veins, and the most important segments are those that belong simultaneously to two of these principal cycles. Each principal cycle contains a series of smaller cycles of veins of lower transport efficiency, thus reflecting the hierarchical and self-similar structure of the transportation network. Finally, we calculate accessibility maps that show how easily different nodes of the network may be reached from a given reference node. (paper)

  13. Three-Dimensional Vascular Network Assembly From Diabetic Patient-Derived Induced Pluripotent Stem Cells.

    Science.gov (United States)

    Chan, Xin Yi; Black, Rebecca; Dickerman, Kayla; Federico, Joseph; Lévesque, Mathieu; Mumm, Jeff; Gerecht, Sharon

    2015-12-01

    In diabetics, hyperglycemia results in deficient endothelial progenitors and cells, leading to cardiovascular complications. We aim to engineer 3-dimensional (3D) vascular networks in synthetic hydrogels from type 1 diabetes mellitus (T1D) patient-derived human-induced pluripotent stem cells (hiPSCs), to serve as a transformative autologous vascular therapy for diabetic patients. We validated and optimized an adherent, feeder-free differentiation procedure to derive early vascular cells (EVCs) with high portions of vascular endothelial cadherin-positive cells from hiPSCs. We demonstrate similar differentiation efficiency from hiPSCs derived from healthy donor and patients with T1D. T1D-hiPSC-derived vascular endothelial cadherin-positive cells can mature to functional endothelial cells-expressing mature markers: von Willebrand factor and endothelial nitric oxide synthase are capable of lectin binding and acetylated low-density lipoprotein uptake, form cords in Matrigel and respond to tumor necrosis factor-α. When embedded in engineered hyaluronic acid hydrogels, T1D-EVCs undergo morphogenesis and assemble into 3D networks. When encapsulated in a novel hypoxia-inducible hydrogel, T1D-EVCs respond to low oxygen and form 3D networks. As xenografts, T1D-EVCs incorporate into developing zebrafish vasculature. Using our robust protocol, we can direct efficient differentiation of T1D-hiPSC to EVCs. Early endothelial cells derived from T1D-hiPSC are functional when mature. T1D-EVCs self-assembled into 3D networks when embedded in hyaluronic acid and hypoxia-inducible hydrogels. The capability of T1D-EVCs to assemble into 3D networks in engineered matrices and to respond to a hypoxic microenvironment is a significant advancement for autologous vascular therapy in diabetic patients and has broad importance for tissue engineering. © 2015 American Heart Association, Inc.

  14. A generative modeling approach to connectivity-Electrical conduction in vascular networks

    DEFF Research Database (Denmark)

    Hald, Bjørn Olav

    2016-01-01

    The physiology of biological structures is inherently dynamic and emerges from the interaction and assembly of large collections of small entities. The extent of coupled entities complicates modeling and increases computational load. Here, microvascular networks are used to present a novel...... to synchronize vessel tone across the vast distances within a network. We hypothesize that electrical conduction capacity is delimited by the size of vascular structures and connectivity of the network. Generation and simulation of series of dynamical models of electrical spread within vascular networks...... of different size and composition showed that (1) Conduction is enhanced in models harboring long and thin endothelial cells that couple preferentially along the longitudinal axis. (2) Conduction across a branch point depends on endothelial connectivity between branches. (3) Low connectivity sub...

  15. PageRank model of opinion formation on Ulam networks

    Science.gov (United States)

    Chakhmakhchyan, L.; Shepelyansky, D.

    2013-12-01

    We consider a PageRank model of opinion formation on Ulam networks, generated by the intermittency map and the typical Chirikov map. The Ulam networks generated by these maps have certain similarities with such scale-free networks as the World Wide Web (WWW), showing an algebraic decay of the PageRank probability. We find that the opinion formation process on Ulam networks has certain similarities but also distinct features comparing to the WWW. We attribute these distinctions to internal differences in network structure of the Ulam and WWW networks. We also analyze the process of opinion formation in the frame of generalized Sznajd model which protects opinion of small communities.

  16. Image-guided, Laser-based Fabrication of Vascular-derived Microfluidic Networks

    OpenAIRE

    Heintz, Keely A.; Mayerich, David; Slater, John H.

    2017-01-01

    This detailed protocol outlines the implementation of image-guided, laser-based hydrogel degradation for the fabrication of vascular-derived microfluidic networks embedded in PEGDA hydrogels. Here, we describe the creation of virtual masks that allow for image-guided laser control; the photopolymerization of a micromolded PEGDA hydrogel, suitable for microfluidic network fabrication and pressure head-driven flow; the setup and use of a commercially available laser scanning confocal microscope...

  17. Social network composition of vascular patients and its associations with health behavior and clinical risk factors

    NARCIS (Netherlands)

    Heijmans, N.; Lieshout, J. van; Wensing, M.

    2017-01-01

    BACKGROUND: This study aimed to explore linkages of patients' social network composition with health behaviors and clinical risk factors. METHODS/DESIGN: This observational study was embedded in a project aimed at improving cardiovascular risk management (CRVM) in primary care. 657 vascular patients

  18. The Role of Trust in Costly Network Formation

    NARCIS (Netherlands)

    Gilles, R.P.; Sarangi, S.

    2003-01-01

    We consider game theoretic models of social network formation.In this paper we limit our investigation to game theoretic models of network formation that are based on individual actions only.Our approach is based on three simple and realistic principles: (1) Link formation is a binary process of

  19. Epigenetic regulation of vascular smooth muscle cell proliferation and neointima formation by histone deacetylase inhibition.

    Science.gov (United States)

    Findeisen, Hannes M; Gizard, Florence; Zhao, Yue; Qing, Hua; Heywood, Elizabeth B; Jones, Karrie L; Cohn, Dianne; Bruemmer, Dennis

    2011-04-01

    Proliferation of smooth muscle cells (SMC) in response to vascular injury is central to neointimal vascular remodeling. There is accumulating evidence that histone acetylation constitutes a major epigenetic modification for the transcriptional control of proliferative gene expression; however, the physiological role of histone acetylation for proliferative vascular disease remains elusive. In the present study, we investigated the role of histone deacetylase (HDAC) inhibition in SMC proliferation and neointimal remodeling. We demonstrate that mitogens induce transcription of HDAC 1, 2, and 3 in SMC. Short interfering RNA-mediated knockdown of either HDAC 1, 2, or 3 and pharmacological inhibition of HDAC prevented mitogen-induced SMC proliferation. The mechanisms underlying this reduction of SMC proliferation by HDAC inhibition involve a growth arrest in the G(1) phase of the cell cycle that is due to an inhibition of retinoblastoma protein phosphorylation. HDAC inhibition resulted in a transcriptional and posttranscriptional regulation of the cyclin-dependent kinase inhibitors p21(Cip1) and p27(Kip). Furthermore, HDAC inhibition repressed mitogen-induced cyclin D1 mRNA expression and cyclin D1 promoter activity. As a result of this differential cell cycle-regulatory gene expression by HDAC inhibition, the retinoblastoma protein retains a transcriptional repression of its downstream target genes required for S phase entry. Finally, we provide evidence that these observations are applicable in vivo by demonstrating that HDAC inhibition decreased neointima formation and expression of cyclin D1 in a murine model of vascular injury. These findings identify HDAC as a critical component of a transcriptional cascade regulating SMC proliferation and suggest that HDAC might play a pivotal role in the development of proliferative vascular diseases, including atherosclerosis and in-stent restenosis.

  20. Magnolol inhibits migration of vascular smooth muscle cells via cytoskeletal remodeling pathway to attenuate neointima formation

    International Nuclear Information System (INIS)

    Karki, Rajendra; Kim, Seong-Bin; Kim, Dong-Wook

    2013-01-01

    Background: Increased proliferation and migration of vascular smooth muscle cells (VSMCs) contribute importantly to the formation of both atherosclerotic and restenotic lesions. The objective of this study was to investigate the effect of magnolol on VSMC migration. Methods: The proteolytic activity of matrix metalloproteinases (MMPs) in tumor necrosis factor alpha (TNF-α) stimulated VSMCs was performed by gelatin zymography. VSMC migration was assessed by wound healing and Boyden chamber methods. Collagen induced VSMC adhesion was determined by spectrofluorimeter and stress fibers formation was evaluated by fluorescence microscope. The expression of signaling molecules involved in stress fibers formation was determined by western blot. The phosphorylation of myosin light chain (MLC20) was determined by urea-glycerol polyacrylamide gel electrophoresis. Immunohistochemistry was performed to determine the expression of β1-integrin and collagen type I in the injured carotid arteries of rats on day 35 after vascular injury. Results: VSMC migration was strongly inhibited by magnolol without affecting MMPs expression. Also, magnolol inhibited β1-integrin expression, FAK phosphorylation and RhoA and Cdc42 activation to inhibit the collagen induced stress fibers formation. Moreover, magnolol inhibited the phosphorylation of MLC20. Our in vivo results showed that magnolol inhibited β1-integrin expression, collagen type I deposition and FAK phosphorylation in injured carotid arteries without affecting MMP-2 activity. Conclusions: Magnolol inhibited VSMC migration via inhibition of cytoskeletal remodeling pathway to attenuate neointima formation. General significance: This study provides a rationale for further evaluation of magnolol for the management of atherosclerosis and restenosis. - Highlights: • Magnolol strongly inhibited migration of VSMCs. • Magnolol inhibited stress fibers formation. • MLC20 phosphorylation was also inhibited by magnolol. • Anti

  1. Magnolol inhibits migration of vascular smooth muscle cells via cytoskeletal remodeling pathway to attenuate neointima formation

    Energy Technology Data Exchange (ETDEWEB)

    Karki, Rajendra [Division of Pharmacology and Toxicology, School of Pharmacy, University of Missouri-Kansas City (United States); Department of Oriental Medicine Resources, Mokpo National University (Korea, Republic of); Kim, Seong-Bin [Jeollanamdo Development Institute for Korean Traditional Medicine, Jangheung gun, Jeollanamdo (Korea, Republic of); Kim, Dong-Wook, E-mail: dbkim@mokpo.ac.kr [Department of Oriental Medicine Resources, Mokpo National University (Korea, Republic of)

    2013-12-10

    Background: Increased proliferation and migration of vascular smooth muscle cells (VSMCs) contribute importantly to the formation of both atherosclerotic and restenotic lesions. The objective of this study was to investigate the effect of magnolol on VSMC migration. Methods: The proteolytic activity of matrix metalloproteinases (MMPs) in tumor necrosis factor alpha (TNF-α) stimulated VSMCs was performed by gelatin zymography. VSMC migration was assessed by wound healing and Boyden chamber methods. Collagen induced VSMC adhesion was determined by spectrofluorimeter and stress fibers formation was evaluated by fluorescence microscope. The expression of signaling molecules involved in stress fibers formation was determined by western blot. The phosphorylation of myosin light chain (MLC20) was determined by urea-glycerol polyacrylamide gel electrophoresis. Immunohistochemistry was performed to determine the expression of β1-integrin and collagen type I in the injured carotid arteries of rats on day 35 after vascular injury. Results: VSMC migration was strongly inhibited by magnolol without affecting MMPs expression. Also, magnolol inhibited β1-integrin expression, FAK phosphorylation and RhoA and Cdc42 activation to inhibit the collagen induced stress fibers formation. Moreover, magnolol inhibited the phosphorylation of MLC20. Our in vivo results showed that magnolol inhibited β1-integrin expression, collagen type I deposition and FAK phosphorylation in injured carotid arteries without affecting MMP-2 activity. Conclusions: Magnolol inhibited VSMC migration via inhibition of cytoskeletal remodeling pathway to attenuate neointima formation. General significance: This study provides a rationale for further evaluation of magnolol for the management of atherosclerosis and restenosis. - Highlights: • Magnolol strongly inhibited migration of VSMCs. • Magnolol inhibited stress fibers formation. • MLC20 phosphorylation was also inhibited by magnolol. • Anti

  2. Ethylene-Related Gene Expression Networks in Wood Formation

    Directory of Open Access Journals (Sweden)

    Carolin Seyfferth

    2018-03-01

    Full Text Available Thickening of tree stems is the result of secondary growth, accomplished by the meristematic activity of the vascular cambium. Secondary growth of the stem entails developmental cascades resulting in the formation of secondary phloem outwards and secondary xylem (i.e., wood inwards of the stem. Signaling and transcriptional reprogramming by the phytohormone ethylene modifies cambial growth and cell differentiation, but the molecular link between ethylene and secondary growth remains unknown. We addressed this shortcoming by analyzing expression profiles and co-expression networks of ethylene pathway genes using the AspWood transcriptome database which covers all stages of secondary growth in aspen (Populus tremula stems. ACC synthase expression suggests that the ethylene precursor 1-aminocyclopropane-1-carboxylic acid (ACC is synthesized during xylem expansion and xylem cell maturation. Ethylene-mediated transcriptional reprogramming occurs during all stages of secondary growth, as deduced from AspWood expression profiles of ethylene-responsive genes. A network centrality analysis of the AspWood dataset identified EIN3D and 11 ERFs as hubs. No overlap was found between the co-expressed genes of the EIN3 and ERF hubs, suggesting target diversification and hence independent roles for these transcription factor families during normal wood formation. The EIN3D hub was part of a large co-expression gene module, which contained 16 transcription factors, among them several new candidates that have not been earlier connected to wood formation and a VND-INTERACTING 2 (VNI2 homolog. We experimentally demonstrated Populus EIN3D function in ethylene signaling in Arabidopsis thaliana. The ERF hubs ERF118 and ERF119 were connected on the basis of their expression pattern and gene co-expression module composition to xylem cell expansion and secondary cell wall formation, respectively. We hereby establish data resources for ethylene-responsive genes and

  3. Progressively Disrupted Brain Functional Connectivity Network in Subcortical Ischemic Vascular Cognitive Impairment Patients.

    Science.gov (United States)

    Sang, Linqiong; Chen, Lin; Wang, Li; Zhang, Jingna; Zhang, Ye; Li, Pengyue; Li, Chuanming; Qiu, Mingguo

    2018-01-01

    Cognitive impairment caused by subcortical ischemic vascular disease (SIVD) has been elucidated by many neuroimaging studies. However, little is known regarding the changes in brain functional connectivity networks in relation to the severity of cognitive impairment in SIVD. In the present study, 20 subcortical ischemic vascular cognitive impairment no dementia patients (SIVCIND) and 20 dementia patients (SIVaD) were enrolled; additionally, 19 normal controls were recruited. Each participant underwent a resting-state functional MRI scan. Whole-brain functional networks were analyzed with graph theory and network-based statistics (NBS) to study the functional organization of networks and find alterations in functional connectivity among brain regions. After adjustments for age, gender, and duration of formal education, there were significant group differences for two network functional organization indices, global efficiency and local efficiency, which decreased (NC > SIVCIND > SIVaD) as cognitive impairment worsened. Between-group differences in functional connectivity (NBS corrected, p  impairment worsened, with an increased number of decreased connections between brain regions. We also observed more reductions in nodal efficiency in the prefrontal and temporal cortices for SIVaD than for SIVCIND. These findings indicated a progressively disrupted pattern of the brain functional connectivity network with increased cognitive impairment and showed promise for the development of reliable biomarkers of network metric changes related to cognitive impairment caused by SIVD.

  4. Omentopexy improves vascularization and decreases stricture formation of esophageal anastomoses in a dog model.

    Science.gov (United States)

    Hayari, Lili; Hershko, Dan D; Shoshani, Hadas; Maor, Ron; Mordecovich, Daniel; Shoshani, Gideon

    2004-04-01

    Anastomotic strictures are common after primary esophageal anastomosis in pediatric patients. Recent studies provided evidence that omentopexy may improve vascularization of gastroesophageal anastomoses and decrease the rate of stricture-related complications. The effect of omentopexy on primary esophago-esophageal anastomosis, however, is unknown. The aim of the current study was to examine the role of omentopexy on the healing process of primary midesopageal anastomoses. Six dogs were operated on. A 5-cm portion of the midesophagus was resected, and continuity was restored by end-to-end anastomosis. In 3 dogs, an omental pedicle was placed around the anastomotic region. Eating patterns were recorded and functional swallowing was evaluated by fluoroscopic studies. Eight weeks after the operations, the experimental animals were killed and anastomotic lumen diameters and vascularization of the anastomotic sites were evaluated by radiographic studies and histologic examination, respectively. Two dogs in the omentopexy group were able to resume regular feeding, whereas none of the dogs in the control group were able to tolerate solid food intake. Fluoroscopic studies found preserved motility patterns of the esophagus in the omentoesophagopexy group, while prestenotic dilatation and delayed food clearance through the anastomosis were observed in the control group. Histologically, neovascularization was observed at the anastomotic site in the omentoesophagopexy group in contrast to the marked degree of fibrosis displayed in the control group. Omentopexy may improve vascularization and decrease stricture formation after primary esophagoesophageal anastomosis.

  5. A meta-analysis of aneurysm formation in laser assisted vascular anastomosis (LAVA)

    Science.gov (United States)

    Chen, Chen; Peng, Fei; Xu, Dahai; Cheng, Qinghua

    2009-08-01

    Laser assisted vascular anastomosis (LAVA) is looked as a particularly promising non-suture method in future. However, aneurysm formation is one of the main reasons delay the clinical application of LAVA. Some scientists investigated the incidence of aneurysms in animal model. To systematically analyze the literature on reported incidence of aneurysm formation in LAVA therapy, we performed a meta-analysis comparing LAVA with conventional suture anastomosis (CSA) in animal model. Data were systematically retrieved and selected from PUBMED. In total, 23 studies were retrieved. 18 studies were excluded, and 5 studies involving 647 animals were included. Analysis suggested no statistically significant difference between LAVA and CSA (OR 1.24, 95%CI 0.66-2.32, P=0.51). Result of meta analysis shows that the technology of LAVA is very close to clinical application.

  6. Phenotypic modulation of smooth muscle cells during formation of neointimal thickenings following vascular injury.

    Science.gov (United States)

    Thyberg, J

    1998-07-01

    Smooth muscle cells build up the media of mammalian arteries and constitute one of the principal cell types in atherosclerotic and restenotic lesions. Accordingly, they show a high degree of plasticity and are able to shift from a differentiated, contractile phenotype to a less differentiated, synthetic phenotype, and then back again. This modulation occurs as a response to vascular injury and includes a prominent structural reorganization with loss of myofilaments and formation of an extensive endoplasmic reticulum and a large Golgi complex. At the same time, the expression of cytoskeletal proteins and other gene products is altered. As a result, the cells lose their contractility and become able to migrate from the media to the intima, proliferate, and secrete extracellular matrix components, thereby contributing to the formation of intimal thickenings. The mechanisms behind this change in morphology and function of the smooth muscle cells are still incompletely understood. A crucial role has been ascribed to basement membrane proteins such as laminin and collagen type IV and adhesive proteins such as fibronectin. A significant role is also played by mitogenic proteins such as platelet-derived growth factor (PDGF) and basic fibroblast growth factor (bFGF). An improved knowledge of the regulation of smooth muscle differentiated properties represents an important part in the search for new methods of prevention and treatment of vascular disease.

  7. Overexpression of Catalase in Vascular Smooth Muscle Cells Prevents the Formation of Abdominal Aortic Aneurysms

    Science.gov (United States)

    Parastatidis, Ioannis; Weiss, Daiana; Joseph, Giji; Taylor, W Robert

    2013-01-01

    Objective Elevated levels of oxidative stress have been reported in abdominal aortic aneurysms (AAA), but which reactive oxygen species (ROS) promotes the development of AAA remains unclear. Here we investigate the effect of the hydrogen peroxide (H2O2) degrading enzyme catalase on the formation of AAA. Approach and Results AAA were induced with the application of calcium chloride (CaCl2) on mouse infrarenal aortas. The administration of PEG-catalase, but not saline, attenuated the loss of tunica media and protected against AAA formation (0.91±0.1 mm vs. 0.76±0.09 mm). Similarly, in a transgenic mouse model, catalase over-expression in the vascular smooth muscle cells (VSMC) preserved the thickness of tunica media and inhibited aortic dilatation by 50% (0.85±0.14 mm vs. 0.57±0.08 mm). Further studies showed that injury with CaCl2 decreased catalase expression and activity in the aortic wall. Pharmacologic administration or genetic over-expression of catalase restored catalase activity and subsequently decreased matrix metalloproteinase activity. In addition, a profound reduction in inflammatory markers and VSMC apoptosis was evident in aortas of catalase over-expressing mice. Interestingly, as opposed to infusion of PEG-catalase, chronic over-expression of catalase in VSMC did not alter the total aortic H2O2 levels. Conclusions The data suggest that a reduction in aortic wall catalase activity can predispose to AAA formation. Restoration of catalase activity in the vascular wall enhances aortic VSMC survival and prevents AAA formation primarily through modulation of matrix metalloproteinase activity. PMID:23950141

  8. Network formation under heterogeneous costs: The multiple group model

    NARCIS (Netherlands)

    Kamphorst, J.J.A.; van der Laan, G.

    2007-01-01

    It is widely recognized that the shape of networks influences both individual and aggregate behavior. This raises the question which types of networks are likely to arise. In this paper we investigate a model of network formation, where players are divided into groups and the costs of a link between

  9. Assembly and patterning of the vascular network of the vertebrate hindbrain

    OpenAIRE

    Fujita, Misato; Cha, Young R.; Pham, Van N.; Sakurai, Atsuko; Roman, Beth L.; Gutkind, J. Silvio; Weinstein, Brant M.

    2011-01-01

    The cranial vasculature is essential for the survival and development of the central nervous system and is important in stroke and other brain pathologies. Cranial vessels form in a reproducible and evolutionarily conserved manner, but the process by which these vessels assemble and acquire their stereotypic patterning remains unclear. Here, we examine the stepwise assembly and patterning of the vascular network of the zebrafish hindbrain. The major artery supplying the hindbrain, the basilar...

  10. Social network composition of vascular patients and its associations with health behavior and clinical risk factors.

    Directory of Open Access Journals (Sweden)

    Naomi Heijmans

    Full Text Available This study aimed to explore linkages of patients' social network composition with health behaviors and clinical risk factors.This observational study was embedded in a project aimed at improving cardiovascular risk management (CRVM in primary care. 657 vascular patients (227 with cardiovascular disease, 380 at high vascular risk, mean age 72.4 (SD 9.4 years, were recruited as were individuals patients considered important for dealing with their disease, so called alters (n = 487. Network composition was measured with structured patient questionnaires. Both patients and alters completed questionnaires to measure health behavior (habits for physical activity, diet, and smoking. Clinical risk factors (systolic blood pressure, LDL cholesterol level, and body mass index were extracted from patients' medical records. Six logistic regression analyses, using generalized estimating equations, were used to test three hypothesized effects of network composition (having alters with healthful behaviors, without depression, and with specialized knowledge on six outcomes, adjusted for demographic, personal and psychological characteristics.Having alters with overall healthful behavior was related to healthful patient diet (OR 2.14, 95%CI: 1.52-3.02. Having non-smoking alters in networks was related to reduced odds for patient smoking (OR 0.17, 95%CI: 0.05-0.60. No effects of presence of non-depressed alters were found. Presence of alters with specialized knowledge on CVRM was inversely related to healthful diet habits of patients (OR 0.47, 95%CI 0.24-0.89. No significant associations between social network composition and clinical risk factors were found.Diet and smoking, but not physical exercise and clinical risk factors, were associated with social network composition of patients with vascular conditions. In this study of vascular patients, controlling for both personal and psychological factors, fewer network influences were found compared to previous

  11. PDZK1 prevents neointima formation via suppression of breakpoint cluster region kinase in vascular smooth muscle.

    Directory of Open Access Journals (Sweden)

    Wan Ru Lee

    Full Text Available Scavenger receptor class B, type I (SR-BI and its adaptor protein PDZK1 mediate responses to HDL cholesterol in endothelium. Whether the receptor-adaptor protein tandem serves functions in other vascular cell types is unknown. The current work determined the roles of SR-BI and PDZK1 in vascular smooth muscle (VSM. To evaluate possible VSM functions of SR-BI and PDZK1 in vivo, neointima formation was assessed 21 days post-ligation in the carotid arteries of wild-type, SR-BI-/- or PDZK1-/- mice. Whereas neointima development was negligible in wild-type and SR-BI-/-, there was marked neointima formation in PDZK1-/- mice. PDZK1 expression was demonstrated in primary mouse VSM cells, and compared to wild-type cells, PDZK1-/- VSM displayed exaggerated proliferation and migration in response to platelet derived growth factor (PDGF. Tandem affinity purification-mass spectrometry revealed that PDZK1 interacts with breakpoint cluster region kinase (Bcr, which contains a C-terminal PDZ binding sequence and is known to enhance responses to PDGF in VSM. PDZK1 interaction with Bcr in VSM was demonstrated by pull-down and by coimmunoprecipitation, and the augmented proliferative response to PDGF in PDZK1-/- VSM was abrogated by Bcr depletion. Furthermore, compared with wild-type Bcr overexpression, the introduction of a Bcr mutant incapable of PDZK1 binding into VSM cells yielded an exaggerated proliferative response to PDGF. Thus, PDZK1 has novel SR-BI-independent function in VSM that affords protection from neointima formation, and this involves PDZK1 suppression of VSM cell proliferation via an inhibitory interaction with Bcr.

  12. Metabolic Vascular Syndrome: New Insights into a Multidimensional Network of Risk Factors and Diseases.

    Science.gov (United States)

    Scholz, Gerhard H; Hanefeld, Markolf

    2016-10-01

    Since 1981, we have used the term metabolic syndrome to describe an association of a dysregulation in lipid metabolism (high triglycerides, low high-density lipoprotein cholesterol, disturbed glucose homeostasis (enhanced fasting and/or prandial glucose), gout, and hypertension), with android obesity being based on a common soil (overnutrition, reduced physical activity, sociocultural factors, and genetic predisposition). We hypothesized that main traits of the syndrome occur early and are tightly connected with hyperinsulinemia/insulin resistance, procoagulation, and cardiovascular diseases. To establish a close link between the traits of the metabolic vascular syndrome, we focused our literature search on recent original work and comprehensive reviews dealing with the topics metabolic syndrome, visceral obesity, fatty liver, fat tissue inflammation, insulin resistance, atherogenic dyslipidemia, arterial hypertension, and type 2 diabetes mellitus. Recent research supports the concept that the metabolic vascular syndrome is a multidimensional and interactive network of risk factors and diseases based on individual genetic susceptibility and epigenetic changes where metabolic dysregulation/metabolic inflexibility in different organs and vascular dysfunction are early interconnected. The metabolic vascular syndrome is not only a risk factor constellation but rather a life-long abnormality of a closely connected interactive cluster of developing diseases which escalate each other and should continuously attract the attention of every clinician.

  13. Injectable and inherently vascularizing semi-interpenetrating polymer network for delivering cells to the subcutaneous space.

    Science.gov (United States)

    Mahou, Redouan; Zhang, David K Y; Vlahos, Alexander E; Sefton, Michael V

    2017-07-01

    Injectable hydrogels are suitable for local cell delivery to the subcutaneous space, but the lack of vasculature remains a limiting factor. Previously we demonstrated that biomaterials containing methacrylic acid promoted vascularization. Here we report the preparation of a semi-interpenetrating polymer network (SIPN), and its evaluation as an injectable carrier to deliver cells and generate blood vessels in a subcutaneous implantation site. The SIPN was prepared by reacting a blend of vinyl sulfone-terminated polyethylene glycol (PEG-VS) and sodium polymethacrylate (PMAA-Na) with dithiothreitol. The swelling of SIPN was sensitive to the PMAA-Na content but only small differences in gelation time, permeability and stiffness were noted. SIPN containing 20 mol% PMAA-Na generated a vascular network in the surrounding tissues, with 2-3 times as many vessels as was obtained with 10 mol% PMAA-Na or PEG alone. Perfusion studies showed that the generated vessels were perfused and connected to the host vasculature as early as seven days after transplantation. Islets embedded in SIPN were viable and responsive to glucose stimulation in vitro. In a proof of concept study in a streptozotocin-induced diabetic mouse model, a progressive return to normoglycemia was observed and the presence of insulin positive islets was confirmed when islets were embedded in SIPN prior to delivery. Our approach proposes a biomaterial-mediated strategy to deliver cells while enhancing vascularization. Copyright © 2017 Elsevier Ltd. All rights reserved.

  14. Piperlongumine inhibits atherosclerotic plaque formation and vascular smooth muscle cell proliferation by suppressing PDGF receptor signaling

    Energy Technology Data Exchange (ETDEWEB)

    Son, Dong Ju [Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA (United States); Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (United States); Kim, Soo Yeon [Division of Life Science, Korea Basic Science Institute, Daejeon (Korea, Republic of); Han, Seong Su [University of Iowa Carver College of Medicine, Department of Pathology, Iowa City, IA (United States); Kim, Chan Woo [Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA (United States); Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (United States); Department of Bioinspired Science, Ehwa Womans University, Seoul (Korea, Republic of); Kumar, Sandeep [Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA (United States); Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (United States); Park, Byeoung Soo [Nanotoxtech Co., Ansan (Korea, Republic of); Lee, Sung Eun [Division of Applied Biology and Chemistry, Kyungpook National University, Daegu (Korea, Republic of); Yun, Yeo Pyo [College of Pharmacy, Chungbuk National University, Cheongju (Korea, Republic of); Jo, Hanjoong, E-mail: hjo@emory.edu [Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, GA (United States); Division of Cardiology, Department of Medicine, Emory University, Atlanta, GA (United States); Department of Bioinspired Science, Ehwa Womans University, Seoul (Korea, Republic of); Park, Young Hyun, E-mail: pyh012@sch.ac.kr [Department of Food Science and Nutrition, College of Natural Sciences, Soonchunhyang University, Asan (Korea, Republic of)

    2012-10-19

    Highlights: Black-Right-Pointing-Pointer Anti-atherogenic effect of PL was examined using partial carotid ligation model in ApoE KO mice. Black-Right-Pointing-Pointer PL prevented atherosclerotic plaque development, VSMCs proliferation, and NF-{kappa}B activation. Black-Right-Pointing-Pointer Piperlongumine reduced vascular smooth muscle cell activation through PDGF-R{beta} and NF-{kappa}B-signaling. Black-Right-Pointing-Pointer PL may serve as a new therapeutic molecule for atherosclerosis treatment. -- Abstract: Piperlongumine (piplartine, PL) is an alkaloid found in the long pepper (Piper longum L.) and has well-documented anti-platelet aggregation, anti-inflammatory, and anti-cancer properties; however, the role of PL in prevention of atherosclerosis is unknown. We evaluated the anti-atherosclerotic potential of PL in an in vivo murine model of accelerated atherosclerosis and defined its mechanism of action in aortic vascular smooth muscle cells (VSMCs) in vitro. Local treatment with PL significantly reduced atherosclerotic plaque formation as well as proliferation and nuclear factor-kappa B (NF-{kappa}B) activation in an in vivo setting. PL treatment in VSMCs in vitro showed inhibition of migration and platelet-derived growth factor BB (PDGF-BB)-induced proliferation to the in vivo findings. We further identified that PL inhibited PDGF-BB-induced PDGF receptor beta activation and suppressed downstream signaling molecules such as phospholipase C{gamma}1, extracellular signal-regulated kinases 1 and 2 and Akt. Lastly, PL significantly attenuated activation of NF-{kappa}B-a downstream transcriptional regulator in PDGF receptor signaling, in response to PDGF-BB stimulation. In conclusion, our findings demonstrate a novel, therapeutic mechanism by which PL suppresses atherosclerosis plaque formation in vivo.

  15. Primary Phenomenon in the Network Formation of Endothelial Cells: Effect of Charge.

    Science.gov (United States)

    Arai, Shunto

    2015-12-07

    Blood vessels are essential organs that are involved in the supply of nutrients and oxygen and play an important role in regulating the body's internal environment, including pH, body temperature, and water homeostasis. Many studies have examined the formation of networks of endothelial cells. The results of these studies have revealed that vascular endothelial growth factor (VEGF) affects the interactions of these cells and modulates the network structure. Though almost all previous simulation studies have assumed that the chemoattractant VEGF is present before network formation, vascular endothelial cells secrete VEGF only after the cells bind to the substrate. This suggests VEGF is not essential for vasculogenesis especially at the early stage. Using a simple experiment, we find chain-like structures which last quite longer than it is expected, unless the energetically stable cluster should be compact. Using a purely physical model and simulation, we find that the hydrodynamic interaction retard the compaction of clusters and that the chains are stabilized through the effects of charge. The charge at the surface of the cells affect the interparticle potential, and the resulting repulsive forces prevent the chains from folding. The ions surrounding the cells may also be involved in this process.

  16. Mathematical Analysis of a PDE System for Biological Network Formation

    KAUST Repository

    Haskovec, Jan; Markowich, Peter A.; Perthame, Benoit

    2015-01-01

    Motivated by recent physics papers describing rules for natural network formation, we study an elliptic-parabolic system of partial differential equations proposed by Hu and Cai [13, 15]. The model describes the pressure field thanks to Darcy's type

  17. Capillary network formation from dispersed endothelial cells: Influence of cell traction, cell adhesion, and extracellular matrix rigidity

    Science.gov (United States)

    Ramos, João R. D.; Travasso, Rui; Carvalho, João

    2018-01-01

    The formation of a functional vascular network depends on biological, chemical, and physical processes being extremely well coordinated. Among them, the mechanical properties of the extracellular matrix and cell adhesion are fundamental to achieve a functional network of endothelial cells, able to fully cover a required domain. By the use of a Cellular Potts Model and Finite Element Method it is shown that there exists a range of values of endothelial traction forces, cell-cell adhesion, and matrix rigidities where the network can spontaneously be formed, and its properties are characterized. We obtain the analytical relation that the minimum traction force required for cell network formation must obey. This minimum value for the traction force is approximately independent on the considered cell number and cell-cell adhesion. We quantify how these two parameters influence the morphology of the resulting networks (size and number of meshes).

  18. The construction of digital 3D arterial vascular network of uterine leiomyomas and its clinical significance

    International Nuclear Information System (INIS)

    Chen Chunlin; Xu Yujing; Liu Ping

    2012-01-01

    Objective: To discuss the method of constructing digital 3D arterial vascular network of uterine leiomyomas based on the CTA data, by which to lay the fundamental work for the observation of the origin and distribution of hysteromyoma blood supply. Methods: A total of 64 cases of uterine leiomyomas were enrolled in this study. Dual-source CT angiography was performed in all the patients, and the CTA original images were obtained. By using Mimics 10.01 software the digital 3D arterial vascular network of uterine was reconstructed. The reconstructed models were analyzed. Results: (1) The constructing process of arterial vascular network was successfully accomplished in all 64 patients. The pelvic main arteries, the uterine arteries and tumor-feeding arteries as well as the blood distribution type were clearly demonstrated on the reconstructed images. (2) The origins of hysteromyoma blood supply included uterine artery (81.25%), uterine artery and unilateral ovarian artery (10.94%), uterine artery and bilateral ovarian artery (4.69%) and ovarian artery (3.12%). (3) Distribution pattern of blood supply of uterine leiomyomas could be divided into 4 types: (1) Type Ⅰ. The unilateral arterial blood supply dominant type (unilateral uterine artery with or without ipsilateral ovarian arterial, providing more than 1/2 blood supply of hysteromyoma), which accounted for 35.94% of all patients (23/26); (2) Type Ⅱ. The bilateral arterial blood supply balanced type (bilateral uterine artery with or without ipsilateral ovarian artery, providing about 1/2 blood supply of hysteromyoma), which accounted for 53.13% of all patients (34/64); (3) Type Ⅲ. The unilateral uterine artery was the main blood supply of uterine leiomyomas, which accounted for 7.81% of all patients (5/64); (4) Type Ⅳ. The ovarian artery was the main blood supply of uterine leiomyomas, which accounted for 3.13% of all patients (3/64). Conclusion: Based on CTA data and with the help of reconstruction

  19. Neonatal brain hemorrhage (NBH) of prematurity: translational mechanisms of the vascular-neural network.

    Science.gov (United States)

    Lekic, Tim; Klebe, Damon; Poblete, Roy; Krafft, Paul R; Rolland, William B; Tang, Jiping; Zhang, John H

    2015-01-01

    Neonatal brain hemorrhage (NBH) of prematurity is an unfortunate consequence of preterm birth. Complications result in shunt dependence and long-term structural changes such as posthemorrhagic hydrocephalus, periventricular leukomalacia, gliosis, and neurological dysfunction. Several animal models are available to study this condition, and many basic mechanisms, etiological factors, and outcome consequences, are becoming understood. NBH is an important clinical condition, of which treatment may potentially circumvent shunt complication, and improve functional recovery (cerebral palsy, and cognitive impairments). This review highlights key pathophysiological findings of the neonatal vascular-neural network in the context of molecular mechanisms targeting the posthemorrhagic hydrocephalus affecting this vulnerable infant population.

  20. Neonatal Brain Hemorrhage (NBH) of Prematurity: Translational Mechanisms of the Vascular-Neural Network

    Science.gov (United States)

    Lekic, Tim; Klebe, Damon; Poblete, Roy; Krafft, Paul R.; Rolland, William B.; Tang, Jiping; Zhang, John H.

    2015-01-01

    Neonatal brain hemorrhage (NBH) of prematurity is an unfortunate consequence of preterm birth. Complications result in shunt dependence and long-term structural changes such as post-hemorrhagic hydrocephalus, periventricular leukomalacia, gliosis, and neurological dysfunction. Several animal models are available to study this condition, and many basic mechanisms, etiological factors, and outcome consequences, are becoming understood. NBH is an important clinical condition, of which treatment may potentially circumvent shunt complication, and improve functional recovery (cerebral palsy, and cognitive impairments). This review highlights key pathophysiological findings of the neonatal vascular-neural network in the context of molecular mechanisms targeting the post-hemorrhagic hydrocephalus affecting this vulnerable infant population. PMID:25620100

  1. Vascular Nitric Oxide-Superoxide Balance and Thrombus Formation after Acute Exercise.

    Science.gov (United States)

    Przyborowski, Kamil; Proniewski, Bartosz; Czarny, Joanna; Smeda, Marta; Sitek, Barbara; Zakrzewska, Agnieszka; Zoladz, Jerzy A; Chlopicki, Stefan

    2018-02-21

    An acute bout of strenuous exercise in humans results in transient impairment of NO-dependent function, but it remains unknown whether this phenomenon is associated with increased risk of post-exercise thrombotic events. This study aimed to evaluate effects of a single bout of exhaustive running in mice on the balance of vascular nitric oxide (NO)/reactive oxygen species (ROS) production, and on thrombogenicity. At different time-points (0h, 2h and 4h) after exercise and in sedentary C57BL/6 mice the production of NO and superoxide (O2) in aorta was measured by electron paramagnetic resonance (EPR) spin trapping and by dihydroethidium (DHE)/HPLC-based method, respectively, while collagen-induced thrombus formation was analyzed in a microchip-based flow-chamber system (T-TAS). We also measured pre- and post-exercise plasma concentration of nitrite/nitrate and 6-keto-PGF1α. An acute bout of exhaustive running in mice resulted in decreased production of NO and increased production of O2 in aorta, with maximum changes 2h after completion of exercise when compared to sedentary mice. However, platelet thrombus formation was not changed by exercise as evidenced by unaltered time to start of thrombus formation (T10) and capillary occlusion (OT), and total thrombogenicity (AUC) as measured in a flow-chamber system. Strenuous exercise increased the plasma concentration of nitrite but did not affect nitrate and 6-keto-PGF1α concentrations. An acute bout of strenuous exercise in mice reduced NO and in parallel increased O2 production in aorta. This response was most pronounced 2h after exercise. Surprisingly, the reduced NO and increased O2 production did not result in increased post-exercise platelet-dependent thrombogenicity. These results show that transient reduction in NO bioavailability, caused by exercise-induced oxidative stress, does not modify post-exercise thromboresistance in healthy mice.

  2. Optical coherence tomography angiography retinal vascular network assessment in multiple sclerosis.

    Science.gov (United States)

    Lanzillo, Roberta; Cennamo, Gilda; Criscuolo, Chiara; Carotenuto, Antonio; Velotti, Nunzio; Sparnelli, Federica; Cianflone, Alessandra; Moccia, Marcello; Brescia Morra, Vincenzo

    2017-09-01

    Optical coherence tomography (OCT) angiography is a new method to assess the density of the vascular networks. Vascular abnormalities are considered involved in multiple sclerosis (MS) pathology. To assess the presence of vascular abnormalities in MS and to evaluate their correlation to disease features. A total of 50 MS patients with and without history of optic neuritis (ON) and 46 healthy subjects were included. All underwent spectral domain (SD)-OCT and OCT angiography. Clinical history, Expanded Disability Status Scale (EDSS), Multiple Sclerosis Severity Score (MSSS) and disease duration were collected. Angio-OCT showed a vessel density reduction in eyes of MS patients when compared to controls. A statistically significant reduction in all SD-OCT and OCT angiography parameters was noticed both in eyes with and without ON when compared with control eyes. We found an inverse correlation between SD-OCT parameters and MSSS ( p = 0.003) and between vessel density parameters and EDSS ( p = 0.007). We report a vessel density reduction in retina of MS patients. We highlight the clinical correlation between vessel density and EDSS, suggesting that angio-OCT could be a good marker of disease and of disability in MS.

  3. Mathematical Analysis of a PDE System for Biological Network Formation

    KAUST Repository

    Haskovec, Jan

    2015-02-04

    Motivated by recent physics papers describing rules for natural network formation, we study an elliptic-parabolic system of partial differential equations proposed by Hu and Cai [13, 15]. The model describes the pressure field thanks to Darcy\\'s type equation and the dynamics of the conductance network under pressure force effects with a diffusion rate D >= 0 representing randomness in the material structure. We prove the existence of global weak solutions and of local mild solutions and study their long term behavior. It turns out that, by energy dissipation, steady states play a central role to understand the network formation capacity of the system. We show that for a large diffusion coefficient D, the zero steady state is stable, while network formation occurs for small values of D due to the instability of the zero steady state, and the borderline case D = 0 exhibits a large class of dynamically stable (in the linearized sense) steady states.

  4. Social power and opinion formation in complex networks

    Science.gov (United States)

    Jalili, Mahdi

    2013-02-01

    In this paper we investigate the effects of social power on the evolution of opinions in model networks as well as in a number of real social networks. A continuous opinion formation model is considered and the analysis is performed through numerical simulation. Social power is given to a proportion of agents selected either randomly or based on their degrees. As artificial network structures, we consider scale-free networks constructed through preferential attachment and Watts-Strogatz networks. Numerical simulations show that scale-free networks with degree-based social power on the hub nodes have an optimal case where the largest number of the nodes reaches a consensus. However, given power to a random selection of nodes could not improve consensus properties. Introducing social power in Watts-Strogatz networks could not significantly change the consensus profile.

  5. Disrupted topological organization of resting-state functional brain network in subcortical vascular mild cognitive impairment.

    Science.gov (United States)

    Yi, Li-Ye; Liang, Xia; Liu, Da-Ming; Sun, Bo; Ying, Sun; Yang, Dong-Bo; Li, Qing-Bin; Jiang, Chuan-Lu; Han, Ying

    2015-10-01

    Neuroimaging studies have demonstrated both structural and functional abnormalities in widespread brain regions in patients with subcortical vascular mild cognitive impairment (svMCI). However, whether and how these changes alter functional brain network organization remains largely unknown. We recruited 21 patients with svMCI and 26 healthy control (HC) subjects who underwent resting-state functional magnetic resonance imaging scans. Graph theory-based network analyses were used to investigate alterations in the topological organization of functional brain networks. Compared with the HC individuals, the patients with svMCI showed disrupted global network topology with significantly increased path length and modularity. Modular structure was also impaired in the svMCI patients with a notable rearrangement of the executive control module, where the parietal regions were split out and grouped as a separate module. The svMCI patients also revealed deficits in the intra- and/or intermodule connectivity of several brain regions. Specifically, the within-module degree was decreased in the middle cingulate gyrus while it was increased in the left anterior insula, medial prefrontal cortex and cuneus. Additionally, increased intermodule connectivity was observed in the inferior and superior parietal gyrus, which was associated with worse cognitive performance in the svMCI patients. Together, our results indicate that svMCI patients exhibit dysregulation of the topological organization of functional brain networks, which has important implications for understanding the pathophysiological mechanism of svMCI. © 2015 John Wiley & Sons Ltd.

  6. Overlapping coalition formation games in wireless communication networks

    CERN Document Server

    Wang, Tianyu; Saad, Walid; Han, Zhu

    2017-01-01

    This brief introduces overlapping coalition formation games (OCF games), a novel mathematical framework from cooperative game theory that can be used to model, design and analyze cooperative scenarios in future wireless communication networks. The concepts of OCF games are explained, and several algorithmic aspects are studied. In addition, several major application scenarios are discussed. These applications are drawn from a variety of fields that include radio resource allocation in dense wireless networks, cooperative spectrum sensing for cognitive radio networks, and resource management for crowd sourcing. For each application, the use of OCF games is discussed in detail in order to show how this framework can be used to solve relevant wireless networking problems. Overlapping Coalition Formation Games in Wireless Communication Networks provides researchers, students and practitioners with a concise overview of existing works in this emerging area, exploring the relevant fundamental theories, key techniqu...

  7. Causal biological network database: a comprehensive platform of causal biological network models focused on the pulmonary and vascular systems.

    Science.gov (United States)

    Boué, Stéphanie; Talikka, Marja; Westra, Jurjen Willem; Hayes, William; Di Fabio, Anselmo; Park, Jennifer; Schlage, Walter K; Sewer, Alain; Fields, Brett; Ansari, Sam; Martin, Florian; Veljkovic, Emilija; Kenney, Renee; Peitsch, Manuel C; Hoeng, Julia

    2015-01-01

    With the wealth of publications and data available, powerful and transparent computational approaches are required to represent measured data and scientific knowledge in a computable and searchable format. We developed a set of biological network models, scripted in the Biological Expression Language, that reflect causal signaling pathways across a wide range of biological processes, including cell fate, cell stress, cell proliferation, inflammation, tissue repair and angiogenesis in the pulmonary and cardiovascular context. This comprehensive collection of networks is now freely available to the scientific community in a centralized web-based repository, the Causal Biological Network database, which is composed of over 120 manually curated and well annotated biological network models and can be accessed at http://causalbionet.com. The website accesses a MongoDB, which stores all versions of the networks as JSON objects and allows users to search for genes, proteins, biological processes, small molecules and keywords in the network descriptions to retrieve biological networks of interest. The content of the networks can be visualized and browsed. Nodes and edges can be filtered and all supporting evidence for the edges can be browsed and is linked to the original articles in PubMed. Moreover, networks may be downloaded for further visualization and evaluation. Database URL: http://causalbionet.com © The Author(s) 2015. Published by Oxford University Press.

  8. Influence of vascular network design on gas transfer in lung assist device technology.

    Science.gov (United States)

    Bassett, Erik K; Hoganson, David M; Lo, Justin H; Penson, Elliot J N; Vacanti, Joseph P

    2011-01-01

    Blood oxygenators are vital for the critically ill, but their use is limited to the hospital setting. A portable blood oxygenator or a lung assist device for ambulatory or long-term use would greatly benefit patients with chronic lung disease. In this work, a biomimetic blood oxygenator system was developed which consisted of a microfluidic vascular network covered by a gas permeable silicone membrane. This system was used to determine the influence of key microfluidic parameters-channel size, oxygen exposure length, and blood shear rate-on blood oxygenation and carbon dioxide removal. Total gas transfer increased linearly with flow rate, independent of channel size and oxygen exposure length. On average, CO(2) transfer was 4.3 times higher than oxygen transfer. Blood oxygen saturation was also found to depend on the flow rate per channel but in an inverse manner; oxygenation decreased and approached an asymptote as the flow rate per channel increased. These relationships can be used to optimize future biomimetic vascular networks for specific lung applications: gas transfer for carbon dioxide removal in patients with chronic obstructive pulmonary disease or oxygenation for premature infants requiring complete lung replacement therapy.

  9. MFAP4 Promotes Vascular Smooth Muscle Migration, Proliferation and Accelerates Neointima Formation

    DEFF Research Database (Denmark)

    Schlosser, Anders; Pilecki, Bartosz; Hemstra, Line E.

    2016-01-01

    in the vascular wall. The role of MFAP4 in vascular biology is unknown. We aimed to test the hypothesis that MFAP4 would enhance integrin-dependent VSMC activation. APPROACH AND RESULTS: We produced Mfap4-deficient (Mfap4(-/-)) mice and performed carotid artery ligation to explore the role of MFAP4 in vascular...... kinase and downstream kinases. In addition, we showed that MFAP4 promotes monocyte chemotaxis in integrin αVβ3-dependent manner. CONCLUSIONS: MFAP4 regulates integrin αVβ3-induced VSMC proliferation and migration, as well as monocyte chemotaxis, and accelerates neointimal hyperplasia after vascular...

  10. The hemostatic agent ethamsylate promotes platelet/leukocyte aggregate formation in a model of vascular injury.

    Science.gov (United States)

    Hernandez, Maria Rosa; Alvarez-Guerra, Miriam; Escolar, Ginés; Chiavaroli, Carlo; Hannaert, Patrick; Garay, Ricardo P

    2004-08-01

    The hemostatic agent ethamsylate enhances membrane expression of P-selectin in human platelets, but whether this promotes platelet-leukocyte aggregate formation is unknown. Here we investigated this point by flow cytometry determination of human platelet-leukocyte aggregates under basal conditions and after whole-blood perfusion through a damaged rabbit aorta segment. Actions of ethamsylate on adhesive molecules of platelets and leukocytes were investigated in parallel. Under basal conditions, ethamsylate was unable to modify whole-blood platelet-leukocyte aggregation, but following whole-blood perfusion through a damaged vessel, ethamsylate produced a modest, but significant increase in platelet-leukocyte aggregates (48+/-21 and 45+/-26% above control levels at ethamsylate 20 and 40 microm respectively). In isolated leukocyte plasma membranes, 14C-ethamsylate specifically bound up to an amount of 660 pmol/mg protein. Moreover, at concentrations > or =1 microm, ethamsylate induced an important (100-200%) and significant increase in the P-selectin glycoprotein ligand 1 (PSGL-1) fluorescence signal in isolated leukocytes and was unable to significantly modify the percentage of CD11b-positive cells. However, no significant changes in aggregate formation were found when ethamsylate was incubated with isolated leukocytes and blood was reconstituted and perfused. In isolated platelet cell membranes, anti-P-selectin antibody and the anti-integrin RGD-containing pentapeptide (GRDGS) were unable to displace 14C-ethamsylate binding. In conclusion, ethamsylate specifically binds to plasma membranes of leukocytes, enhances membrane PSGL-1 expression and promotes leukocyte-platelet aggregation in whole-blood perfused through a damaged vascular segment. These results together with the previously observed enhancement of platelet P-selectin membrane expression [Thromb. Res. (2002)107:329-335] confirms and extends the view that ethamsylate acts on the first step of hemostasis, by

  11. Formation of actin networks in microfluidic concentration gradients

    Directory of Open Access Journals (Sweden)

    Natalja eStrelnikova

    2016-05-01

    Full Text Available The physical properties of cytoskeletal networks are contributors in a number of mechanical responses of cells including cellular deformation and locomotion, and are crucial for the proper action of living cells. Local chemical gradients modulate cytoskeletal functionality including the interactions of the cytoskeleton with other cellular components. Actin is a major constituent of the cytoskeleton. Introducing a microfluidic-based platform, we explored the impact of concentration gradients on the formation and structural properties of actin networks. Microfluidics-controlled flow-free steady state experimental conditions allow for the generation of chemical gradients of different profiles, such as linear or step-like. We discovered specific features of actin networks emerging in defined gradients. In particular, we analyzed the effects of spatial conditions on network properties, bending rigidities of network links, and the network elasticity.

  12. Bump formation in a binary attractor neural network

    International Nuclear Information System (INIS)

    Koroutchev, Kostadin; Korutcheva, Elka

    2006-01-01

    The conditions for the formation of local bumps in the activity of binary attractor neural networks with spatially dependent connectivity are investigated. We show that these formations are observed when asymmetry between the activity during the retrieval and learning is imposed. An analytical approximation for the order parameters is derived. The corresponding phase diagram shows a relatively large and stable region where this effect is observed, although critical storage and information capacities drastically decrease inside that region. We demonstrate that the stability of the network, when starting from the bump formation, is larger than the stability when starting even from the whole pattern. Finally, we show a very good agreement between the analytical results and the simulations performed for different topologies of the network

  13. Matrix Metalloproteinases: Inflammatory Regulators of Cell Behaviors in Vascular Formation and Remodeling

    Directory of Open Access Journals (Sweden)

    Qishan Chen

    2013-01-01

    Full Text Available Abnormal angiogenesis and vascular remodeling contribute to pathogenesis of a number of disorders such as tumor, arthritis, atherosclerosis, restenosis, hypertension, and neurodegeneration. During angiogenesis and vascular remodeling, behaviors of stem/progenitor cells, endothelial cells (ECs, and vascular smooth muscle cells (VSMCs and its interaction with extracellular matrix (ECM play a critical role in the processes. Matrix metalloproteinases (MMPs, well-known inflammatory mediators are a family of zinc-dependent proteolytic enzymes that degrade various components of ECM and non-ECM molecules mediating tissue remodeling in both physiological and pathological processes. MMPs including MMP-1, MMP-2, MMP-3, MMP-7, MMP-8, MMP-9, MMP-12, and MT1-MMP, are stimulated and activated by various stimuli in vascular tissues. Once activated, MMPs degrade ECM proteins or other related signal molecules to promote recruitment of stem/progenitor cells and facilitate migration and invasion of ECs and VSMCs. Moreover, vascular cell proliferation and apoptosis can also be regulated by MMPs via proteolytically cleaving and modulating bioactive molecules and relevant signaling pathways. Regarding the importance of vascular cells in abnormal angiogenesis and vascular remodeling, regulation of vascular cell behaviors through modulating expression and activation of MMPs shows therapeutic potential.

  14. Vascular endothelial growth factor modified macrophages transdifferentiate into endothelial-like cells and decrease foam cell formation.

    Science.gov (United States)

    Yan, Dan; He, Yujuan; Dai, Jun; Yang, Lili; Wang, Xiaoyan; Ruan, Qiurong

    2017-06-30

    Macrophages are largely involved in the whole process of atherosclerosis from an initiation lesion to an advanced lesion. Endothelial disruption is the initial step and macrophage-derived foam cells are the hallmark of atherosclerosis. Promotion of vascular integrity and inhibition of foam cell formation are two important strategies for preventing atherosclerosis. How can we inhibit even the reverse negative role of macrophages in atherosclerosis? The present study was performed to investigate if overexpressing endogenous human vascular endothelial growth factor (VEGF) could facilitate transdifferentiation of macrophages into endothelial-like cells (ELCs) and inhibit foam cell formation. We demonstrated that VEGF-modified macrophages which stably overexpressed human VEGF (hVEGF 165 ) displayed a high capability to alter their phenotype and function into ELCs in vitro Exogenous VEGF could not replace endogenous VEGF to induce the transdifferentiation of macrophages into ELCs in vitro We further showed that VEGF-modified macrophages significantly decreased cytoplasmic lipid accumulation after treatment with oxidized LDL (ox-LDL). Moreover, down-regulation of CD36 expression in these cells was probably one of the mechanisms of reduction in foam cell formation. Our results provided the in vitro proof of VEGF-modified macrophages as atheroprotective therapeutic cells by both promotion of vascular repair and inhibition of foam cell formation. © 2017 The Author(s).

  15. Intrahepatic Left to Right Portoportal Venous Collateral Vascular Formation in Patients Undergoing Right Portal Vein Ligation

    Energy Technology Data Exchange (ETDEWEB)

    Lienden, K. P. van, E-mail: k.p.vanlienden@amc.uva.nl [Academic Medical Center, University of Amsterdam, Department of Interventional Radiology (Netherlands); Hoekstra, L. T. [Academic Medical Center, University of Amsterdam, Department of Surgery (Netherlands); Bennink, R. J. [Academic Medical Center, University of Amsterdam, Department of Nuclear Medicine (Netherlands); Gulik, T. M. van [Academic Medical Center, University of Amsterdam, Department of Surgery (Netherlands)

    2013-12-15

    Purpose: We investigated intrahepatic vascular changes in patients undergoing right portal vein ligation (PVL) or portal vein embolization (PVE) in conjunction with the ensuing hypertrophic response and function of the left liver lobe. Methods: Between December 2008 and October 2011, 7 patients underwent right PVL and 14 patients PVE. Computed tomographic (CT) volumetry to assess future remnant liver (FRL) and functional hepatobiliary scintigraphy were performed in all patients before and 3 weeks after portal vein occlusion. In 18 patients an intraoperative portography was performed to assess perfusion through the occluded portal branches. Results: In all patients after initially successful PVL, reperfused portal veins were observed on CT scan 3 weeks after portal occlusion. This was confirmed in all cases during intraoperative portography. Intrahepatic portoportal collaterals were identified in all patients in the PVL group and in one patient in the PVE group. In all other PVE patients, complete occlusion of the embolized portal branches was observed on CT scan and on intraoperative portography. The median increase of FRL volume after PVE was 41.6 % (range 10-305 %), and after PVL was only 8.1 % (range 0-102 %) (p = 0.179). There were no differences in FRL function between both groups. Conclusion: Preoperative PVE and PVL are both methods to induce hypertrophy of the FRL in anticipation of major liver resection. Compared to PVE, PVL seems less efficient in inducing hypertrophy of the nonoccluded left lobe. This could be caused by the formation of intrahepatic portoportal neocollateral vessels, through which the ligated portal branches are reperfused within 3 weeks.

  16. Self-healing sandwich structures incorporating an interfacial layer with vascular network

    International Nuclear Information System (INIS)

    Chen, Chunlin; Peters, Kara; Li, Yulong

    2013-01-01

    A self-healing capability specifically targeted for sandwich composite laminates based on interfacial layers with built-in vascular networks is presented. The self-healing occurs at the facesheet–core interface through an additional interfacial layer to seal facesheet cracks and rebond facesheet–core regions. The efficacy of introducing the self-healing system at the facesheet–core interface is evaluated through four-point bend and edgewise compression testing of representative foam core sandwich composite specimens with impact induced damage. The self-healing interfacial layer partially restored the specific initial stiffness, doubling the residual initial stiffness as compared to the control specimen after the impact event. The restoration of the ultimate specific skin strength was less successful. The results also highlight the critical challenge in self-healing of sandwich composites, which is to rebond facesheets which have separated from the core material. (paper)

  17. Magnesium prevents vascular calcification in vitro by inhibition of hydroxyapatite crystal formation.

    NARCIS (Netherlands)

    Braake, A.D. ter; Tinnemans, P.T.; Shanahan, C.M.; Hoenderop, J.G.J.; Baaij, J.H.F. de

    2018-01-01

    Magnesium has been shown to effectively prevent vascular calcification associated with chronic kidney disease. Magnesium has been hypothesized to prevent the upregulation of osteoblastic genes that potentially drives calcification. However, extracellular effects of magnesium on hydroxyapatite

  18. Diagnostic dilemma in vascular mal-formation of the upper lip: a ...

    African Journals Online (AJOL)

    richard

    2014-09-08

    Sep 8, 2014 ... Radiography, Lagos University Teaching Hospital, Lagos. *Corresponding author: ... To present a case of vascular lesion on the upper lip and its management. Methods: We .... midline of the face without bone involvement.

  19. A natural experiment of social network formation and dynamics.

    Science.gov (United States)

    Phan, Tuan Q; Airoldi, Edoardo M

    2015-05-26

    Social networks affect many aspects of life, including the spread of diseases, the diffusion of information, the workers' productivity, and consumers' behavior. Little is known, however, about how these networks form and change. Estimating causal effects and mechanisms that drive social network formation and dynamics is challenging because of the complexity of engineering social relations in a controlled environment, endogeneity between network structure and individual characteristics, and the lack of time-resolved data about individuals' behavior. We leverage data from a sample of 1.5 million college students on Facebook, who wrote more than 630 million messages and 590 million posts over 4 years, to design a long-term natural experiment of friendship formation and social dynamics in the aftermath of a natural disaster. The analysis shows that affected individuals are more likely to strengthen interactions, while maintaining the same number of friends as unaffected individuals. Our findings suggest that the formation of social relationships may serve as a coping mechanism to deal with high-stress situations and build resilience in communities.

  20. Strategies in Interventional Radiology: Formation of an Interdisciplinary Center of Vascular Anomalies - Chances and Challenges for Effective and Efficient Patient Management.

    Science.gov (United States)

    Sadick, Maliha; Dally, Franz Josef; Schönberg, Stefan O; Stroszczynski, Christian; Wohlgemuth, Walter A

    2017-10-01

    Background  Radiology is an interdisciplinary field dedicated to the diagnosis and treatment of numerous diseases and is involved in the development of multimodal treatment concepts. Method  Interdisciplinary case management, a broad spectrum of diagnostic imaging facilities and dedicated endovascular radiological treatment options are valuable tools that allow radiology to set up an interdisciplinary center for vascular anomalies. Results  Image-based diagnosis combined with endovascular treatment options is an essential tool for the treatment of patients with highly complex vascular diseases. These vascular anomalies can affect numerous parts of the body so that a multidisciplinary treatment approach is required for optimal patient care. Conclusion  This paper discusses the possibilities and challenges regarding effective and efficient patient management in connection with the formation of an interdisciplinary center for vascular anomalies with strengthening of the clinical role of radiologists. Key points   · Vascular anomalies, which include vascular tumors and malformations, are complex to diagnose and treat.. · There are far more patients with vascular anomalies requiring therapy than interdisciplinary centers for vascular anomalies - there is currently a shortage of dedicated interdisciplinary centers for vascular anomalies in Germany that can provide dedicated care for affected patients.. · Radiology includes a broad spectrum of diagnostic and minimally invasive therapeutic tools which allow the formation of an interdisciplinary center for vascular anomalies for effective, efficient and comprehensive patient management.. Citation Format · Sadick M, Dally FJ, Schönberg SO et al. Strategies in Interventional Radiology: Formation of an Interdisciplinary Center of Vascular Anomalies - Chances and Challenges for Effective and Efficient Patient Management. Fortschr Röntgenstr 2017; 189: 957 - 966. © Georg Thieme Verlag KG Stuttgart · New

  1. The impact of KRAS mutations on VEGF-A production and tumour vascular network

    International Nuclear Information System (INIS)

    Figueras, Agnès; Arbos, Maria Antonia; Quiles, Maria Teresa; Viñals, Francesc; Germà, Josep Ramón; Capellà, Gabriel

    2013-01-01

    The malignant potential of tumour cells may be influenced by the molecular nature of KRAS mutations being codon 13 mutations less aggressive than codon 12 ones. Their metabolic profile is also different, with an increased anaerobic glycolytic metabolism in cells harbouring codon 12 KRAS mutations compared with cells containing codon 13 mutations. We hypothesized that this distinct metabolic behaviour could be associated with different HIF-1α expression and a distinct angiogenic profile. Codon13 KRAS mutation (ASP13) or codon12 KRAS mutation (CYS12) NIH3T3 transfectants were analyzed in vitro and in vivo. Expression of HIF-1α, and VEGF-A was studied at RNA and protein levels. Regulation of VEGF-A promoter activity was assessed by means of luciferase assays using different plasmid constructs. Vascular network was assessed in tumors growing after subcutaneous inoculation. Non parametric statistics were used for analysis of results. Our results show that in normoxic conditions ASP13 transfectants exhibited less HIF-1α protein levels and activity than CYS12. In contrast, codon 13 transfectants exhibited higher VEGF-A mRNA and protein levels and enhanced VEGF-A promoter activity. These differences were due to a differential activation of Sp1/AP2 transcription elements of the VEGF-A promoter associated with increased ERKs signalling in ASP13 transfectants. Subcutaneous CYS12 tumours expressed less VEGF-A and showed a higher microvessel density (MVD) than ASP13 tumours. In contrast, prominent vessels were only observed in the latter. Subtle changes in the molecular nature of KRAS oncogene activating mutations occurring in tumour cells have a major impact on the vascular strategy devised providing with new insights on the role of KRAS mutations on angiogenesis

  2. Distinctive Resting State Network Disruptions Among Alzheimer's Disease, Subcortical Vascular Dementia, and Mixed Dementia Patients.

    Science.gov (United States)

    Kim, Hee Jin; Cha, Jungho; Lee, Jong-Min; Shin, Ji Soo; Jung, Na-Yeon; Kim, Yeo Jin; Choe, Yearn Seong; Lee, Kyung Han; Kim, Sung Tae; Kim, Jae Seung; Lee, Jae Hong; Na, Duk L; Seo, Sang Won

    2016-01-01

    Recent advances in resting-state functional MRI have revealed altered functional networks in Alzheimer's disease (AD), especially those of the default mode network (DMN) and central executive network (CEN). However, few studies have evaluated whether small vessel disease (SVD) or combined amyloid and SVD burdens affect the DMN or CEN. The aim of this study was to evaluate whether SVD or combined amyloid and SVD burdens affect the DMN or CEN. In this cross-sectional study, we investigated the resting-state functional connectivity within DMN and CEN in 37 Pittsburgh compound-B (PiB)(+) AD, 37 PiB(-) subcortical vascular dementia (SVaD), 13 mixed dementia patients, and 65 normal controls. When the resting-state DMN of PiB(+) AD and PiB(-) SVaD patients were compared, the PiB(+) AD patients displayed lower functional connectivity in the inferior parietal lobule while the PiB(-) SVaD patients displayed lower functional connectivity in the medial frontal and superior frontal gyri. Compared to the PiB(-) SVaD or PiB(+) AD, the mixed dementia patients displayed lower functional connectivity within the DMN in the posterior cingulate gyrus. When the resting-state CEN connectivity of PiB(+) AD and PiB(-) SVaD patients were compared, the PiB(-) SVaD patients displayed lower functional connectivity in the anterior insular region. Compared to the PiB(-) SVaD or PiB(+) AD, the mixed dementia patients displayed lower functional connectivity within the CEN in the inferior frontal gyrus. Our findings suggest that in PiB(+) AD and PiB(-) SVaD, there is divergent disruptions in resting-state DMN and CEN. Furthermore, patients with combined amyloid and SVD burdens exhibited more disrupted resting-state DMN and CEN than patients with only amyloid or SVD burden.

  3. Biofabrication enables efficient interrogation and optimization of sequential culture of endothelial cells, fibroblasts and cardiomyocytes for formation of vascular cords in cardiac tissue engineering

    International Nuclear Information System (INIS)

    Iyer, Rohin K; Radisic, Milica; Chiu, Loraine L Y; Vunjak-Novakovic, Gordana

    2012-01-01

    We previously reported that preculture of fibroblasts (FBs) and endothelial cells (ECs) prior to cardiomyocytes (CMs) improved the structural and functional properties of engineered cardiac tissue compared to culture of CMs alone or co-culture of all three cell types. However, these approaches did not result in formation of capillary-like cords, which are precursors to vascularization in vivo. Here we hypothesized that seeding the ECs first on Matrigel and then FBs 24 h later to stabilize the endothelial network (sequential preculture) would enhance cord formation in engineered cardiac organoids. Three sequential preculture groups were tested by seeding ECs (D4T line) at 8%, 15% and 31% of the total cell number on Matrigel-coated microchannels and incubating for 24 h. Cardiac FBs were then seeded (32%, 25% and 9% of the total cell number, respectively) and incubated an additional 24 h. Finally, neonatal rat CMs (60% of the total cell number) were added and the organoids were cultivated for seven days. Within 24 h, the 8% EC group formed elongated cords which eventually developed into beating cylindrical organoids, while the 15% and 31% EC groups proliferated into flat EC monolayers with poor viability. Excitation threshold (ET) in the 8% EC group (3.4 ± 1.2 V cm −1 ) was comparable to that of the CM group (3.3 ± 1.4 V cm −1 ). The ET worsened with increasing EC seeding density (15% EC: 4.4 ± 1.5 V cm −1 ; 31% EC: 4.9 ± 1.5 V cm −1 ). Thus, sequential preculture promoted vascular cord formation and enhanced architecture and function of engineered heart tissues. (paper)

  4. Opinion formation on multiplex scale-free networks

    Science.gov (United States)

    Nguyen, Vu Xuan; Xiao, Gaoxi; Xu, Xin-Jian; Li, Guoqi; Wang, Zhen

    2018-01-01

    Most individuals, if not all, live in various social networks. The formation of opinion systems is an outcome of social interactions and information propagation occurring in such networks. We study the opinion formation with a new rule of pairwise interactions in the novel version of the well-known Deffuant model on multiplex networks composed of two layers, each of which is a scale-free network. It is found that in a duplex network composed of two identical layers, the presence of the multiplexity helps either diminish or enhance opinion diversity depending on the relative magnitudes of tolerance ranges characterizing the degree of openness/tolerance on both layers: there is a steady separation between different regions of tolerance range values on two network layers where multiplexity plays two different roles, respectively. Additionally, the two critical tolerance ranges follow a one-sum rule; that is, each of the layers reaches a complete consensus only if the sum of the tolerance ranges on the two layers is greater than a constant approximately equaling 1, the double of the critical bound on a corresponding isolated network. A further investigation of the coupling between constituent layers quantified by a link overlap parameter reveals that as the layers are loosely coupled, the two opinion systems co-evolve independently, but when the inter-layer coupling is sufficiently strong, a monotonic behavior is observed: an increase in the tolerance range of a layer causes a decline in the opinion diversity on the other layer regardless of the magnitudes of tolerance ranges associated with the layers in question.

  5. Network formation in a multi-asset artificial stock market

    Science.gov (United States)

    Wu, Songtao; He, Jianmin; Li, Shouwei; Wang, Chao

    2018-04-01

    A multi-asset artificial stock market is developed. In the market, stocks are assigned to a number of sectors and traded by heterogeneous investors. The mechanism of continuous double auction is employed to clear order book and form daily closed prices. Simulation results of prices at the sector level show an intra-sector similarity and inter-sector distinctiveness, and returns of individual stocks have stylized facts that are ubiquitous in the real-world stock market. We find that the market risk factor has critical impact on both network topology transition and connection formation, and that sector risk factors account for the formation of intra-sector links and sector-based local interaction. In addition, the number of community in threshold-based networks is correlated negatively and positively with the value of correlation coefficients and the ratio of intra-sector links, which are respectively determined by intensity of sector risk factors and the number of sectors.

  6. Vascular risk factors, cerebrovascular reactivity, and the default-mode brain network.

    Science.gov (United States)

    Haight, Thaddeus J; Bryan, R Nick; Erus, Guray; Davatzikos, Christos; Jacobs, David R; D'Esposito, Mark; Lewis, Cora E; Launer, Lenore J

    2015-07-15

    Cumulating evidence from epidemiologic studies implicates cardiovascular health and cerebrovascular function in several brain diseases in late life. We examined vascular risk factors with respect to a cerebrovascular measure of brain functioning in subjects in mid-life, which could represent a marker of brain changes in later life. Breath-hold functional MRI (fMRI) was performed in 541 women and men (mean age 50.4 years) from the Coronary Artery Risk Development in Young Adults (CARDIA) Brain MRI sub-study. Cerebrovascular reactivity (CVR) was quantified as percentage change in blood-oxygen level dependent (BOLD) signal in activated voxels, which was mapped to a common brain template and log-transformed. Mean CVR was calculated for anatomic regions underlying the default-mode network (DMN) - a network implicated in AD and other brain disorders - in addition to areas considered to be relatively spared in the disease (e.g. occipital lobe), which were utilized as reference regions. Mean CVR was significantly reduced in the posterior cingulate/precuneus (β=-0.063, 95% CI: -0.106, -0.020), anterior cingulate (β=-0.055, 95% CI: -0.101, -0.010), and medial frontal lobe (β=-0.050, 95% CI: -0.092, -0.008) relative to mean CVR in the occipital lobe, after adjustment for age, sex, race, education, and smoking status, in subjects with pre-hypertension/hypertension compared to normotensive subjects. By contrast, mean CVR was lower, but not significantly, in the inferior parietal lobe (β=-0.024, 95% CI: -0.062, 0.014) and the hippocampus (β=-0.006, 95% CI: -0.062, 0.050) relative to mean CVR in the occipital lobe. Similar results were observed in subjects with diabetes and dyslipidemia compared to those without these conditions, though the differences were non-significant. Reduced CVR may represent diminished vascular functionality for the DMN for individuals with prehypertension/hypertension in mid-life, and may serve as a preclinical marker for brain dysfunction in later

  7. Dynamics of Research Team Formation in Complex Networks

    Science.gov (United States)

    Sun, Caihong; Wan, Yuzi; Chen, Yu

    Most organizations encourage the formation of teams to accomplish complicated tasks, and vice verse, effective teams could bring lots benefits and profits for organizations. Network structure plays an important role in forming teams. In this paper, we specifically study the dynamics of team formation in large research communities in which knowledge of individuals plays an important role on team performance and individual utility. An agent-based model is proposed, in which heterogeneous agents from research communities are described and empirically tested. Each agent has a knowledge endowment and a preference for both income and leisure. Agents provide a variable input (‘effort’) and their knowledge endowments to production. They could learn from others in their team and those who are not in their team but have private connections in community to adjust their own knowledge endowment. They are allowed to join other teams or work alone when it is welfare maximizing to do so. Various simulation experiments are conducted to examine the impacts of network topology, knowledge diffusion among community network, and team output sharing mechanisms on the dynamics of team formation.

  8. Matrix protein of vesicular stomatitis virus: a potent inhibitor of vascular endothelial growth factor and malignant ascites formation.

    Science.gov (United States)

    Zhou, Y; Wen, F; Zhang, P; Tang, R; Li, Q

    2013-03-01

    Malignant ascites is common in various types of cancers and is difficult to manage. Vascular endothelial growth factor (VEGF) has a pivotal role in malignant ascites. The matrix protein of vesicular stomatitis virus (VSVMP) has been shown to inhibit host gene expression and induce the apoptosis of cancer cells. The present study was designed to determine whether VSVMP suppresses the formation of ascites in ascites-producing peritoneal carcinomatosis. BALB/c female mice, 6-8 weeks old, bearing peritoneal tumors of H22 or MethA cells received an intraperitoneal administration of 50 μg VSVMP/250 μg liposome complexes, 50 μg empty plasmid/250 μg liposome complexes or 0.9% NaCl solution, respectively, every 2 days for 3 weeks. Administration of VSVMP resulted in a significant inhibition in ascites formation, improvement in health condition and prolonged survival of the treated mice. Decreased peritoneum osmolarity and reduced tumor vascularity coincided with dramatic reductions in the VEGF level in ascites fluid and plasma. Examination of floating tumor cells collected from the peritoneal wash revealed an apparently increased number of apoptotic cells and profound downregulation of VEGF mRNA in the VSVMP-treated mice. Our data indicate for the first time that in BALB/c mice bearing H22 or MethA cell peritoneal tumors, VSVMP may inhibit VEGF production and suppress angiogenesis, consequently abolishing ascites formation.

  9. [Infectious risk related to the formation of multi-species biofilms (Candida - bacteria) on peripheral vascular catheters].

    Science.gov (United States)

    Seghir, A; Boucherit-Otmani, Z; Sari-Belkharroubi, L; Boucherit, K

    2017-03-01

    The Candida yeasts are the fourth leading cause of death from systemic infections, the risk may increase when the infection also involves bacteria. Yeasts and bacteria can adhere to medical implants, such as peripheral vascular catheters, and form a multicellular structures called "mixed biofilms" more resistant to antimicrobials agents. However, the formation of mixed biofilms on implants leads to long-term persistent infections because they can act as reservoirs of pathogens that have poorly understood interactions. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  10. Wireless network interface energy consumption implications of popular streaming formats

    Science.gov (United States)

    Chandra, Surendar

    2001-12-01

    With the proliferation of mobile streaming multimedia, available battery capacity constrains the end-user experience. Since streaming applications tend to be long running, wireless network interface card's (WNIC) energy consumption is particularly an acute problem. In this work, we explore the WNIC energy consumption implications of popular multimedia streaming formats from Microsoft (Windows media), Real (Real media) and Apple (Quick Time). We investigate the energy consumption under varying stream bandwidth and network loss rates. We also explore history-based client-side strategies to reduce the energy consumed by transitioning the WNICs to a lower power consuming sleep state. We show that Microsoft media tends to transmit packets at regular intervals; streams optimized for 28.8 Kbps can save over 80% in energy consumption with 2% data loss. A high bandwidth stream (768 Kbps) can still save 57% in energy consumption with less than 0.3% data loss. For high bandwidth streams, Microsoft media exploits network-level packet fragmentation, which can lead to excessive packet loss (and wasted energy) in a lossy network. Real stream packets tend to be sent closer to each other, especially at higher bandwidths. Quicktime packets sometimes arrive in quick succession; most likely an application level fragmentation mechanism. Such packets are harder to predict at the network level without understanding the packet semantics.

  11. Interferences between Sphagnum and vascular plants: effects on plant community structure and peat formation

    OpenAIRE

    Malmer, Nils; Albinsson, C; Svensson, B M; Wallén, Bo

    2003-01-01

    The interference between vascular plants and peat mosses with respect to nitrogen and phosphorus was studied in a fertilization experiment and with respect to competition for light in a removal experiment in poor fens with either soligenous or topogenous hydrology using Narthecium ossifragum (L.) Huds. and three species of Sphagnum sect. Sphagnum as targets. Adding fertilizer either on the moss surface or below it confirmed the hypotheses of an asymmetric competition for nutrients, viz. that ...

  12. Directed networks' different link formation mechanisms causing degree distribution distinction

    Science.gov (United States)

    Behfar, Stefan Kambiz; Turkina, Ekaterina; Cohendet, Patrick; Burger-Helmchen, Thierry

    2016-11-01

    Within undirected networks, scientists have shown much interest in presenting power-law features. For instance, Barabási and Albert (1999) claimed that a common property of many large networks is that vertex connectivity follows scale-free power-law distribution, and in another study Barabási et al. (2002) showed power law evolution in the social network of scientific collaboration. At the same time, Jiang et al. (2011) discussed deviation from power-law distribution; others indicated that size effect (Bagrow et al., 2008), information filtering mechanism (Mossa et al., 2002), and birth and death process (Shi et al., 2005) could account for this deviation. Within directed networks, many authors have considered that outlinks follow a similar mechanism of creation as inlinks' (Faloutsos et al., 1999; Krapivsky et al., 2001; Tanimoto, 2009) with link creation rate being the linear function of node degree, resulting in a power-law shape for both indegree and outdegree distribution. Some other authors have made an assumption that directed networks, such as scientific collaboration or citation, behave as undirected, resulting in a power-law degree distribution accordingly (Barabási et al., 2002). At the same time, we claim (1) Outlinks feature different degree distributions than inlinks; where different link formation mechanisms cause the distribution distinctions, (2) in/outdegree distribution distinction holds for different levels of system decomposition; therefore this distribution distinction is a property of directed networks. First, we emphasize in/outlink formation mechanisms as causal factors for distinction between indegree and outdegree distributions (where this distinction has already been noticed in Barker et al. (2010) and Baxter et al. (2006)) within a sample network of OSS projects as well as Java software corpus as a network. Second, we analyze whether this distribution distinction holds for different levels of system decomposition: open

  13. In-silico analysis on biofabricating vascular networks using kinetic Monte Carlo simulations

    International Nuclear Information System (INIS)

    Sun, Yi; Yang, Xiaofeng; Wang, Qi

    2014-01-01

    We present a computational modeling approach to study the fusion of multicellular aggregate systems in a novel scaffold-less biofabrication process, known as ‘bioprinting’. In this novel technology, live multicellular aggregates are used as fundamental building blocks to make tissues or organs (collectively known as the bio-constructs,) via the layer-by-layer deposition technique or other methods; the printed bio-constructs embedded in maturogens, consisting of nutrient-rich bio-compatible hydrogels, are then placed in bioreactors to undergo the cellular aggregate fusion process to form the desired functional bio-structures. Our approach reported here is an agent-based modeling method, which uses the kinetic Monte Carlo (KMC) algorithm to evolve the cellular system on a lattice. In this method, the cells and the hydrogel media, in which cells are embedded, are coarse-grained to material’s points on a three-dimensional (3D) lattice, where the cell–cell and cell–medium interactions are quantified by adhesion and cohesion energies. In a multicellular aggregate system with a fixed number of cells and fixed amount of hydrogel media, where the effect of cell differentiation, proliferation and death are tactically neglected, the interaction energy is primarily dictated by the interfacial energy between cell and cell as well as between cell and medium particles on the lattice, respectively, based on the differential adhesion hypothesis. By using the transition state theory to track the time evolution of the multicellular system while minimizing the interfacial energy, KMC is shown to be an efficient time-dependent simulation tool to study the evolution of the multicellular aggregate system. In this study, numerical experiments are presented to simulate fusion and cell sorting during the biofabrication process of vascular networks, in which the bio-constructs are fabricated via engineering designs. The results predict the feasibility of fabricating the vascular

  14. In-silico analysis on biofabricating vascular networks using kinetic Monte Carlo simulations.

    Science.gov (United States)

    Sun, Yi; Yang, Xiaofeng; Wang, Qi

    2014-03-01

    We present a computational modeling approach to study the fusion of multicellular aggregate systems in a novel scaffold-less biofabrication process, known as 'bioprinting'. In this novel technology, live multicellular aggregates are used as fundamental building blocks to make tissues or organs (collectively known as the bio-constructs,) via the layer-by-layer deposition technique or other methods; the printed bio-constructs embedded in maturogens, consisting of nutrient-rich bio-compatible hydrogels, are then placed in bioreactors to undergo the cellular aggregate fusion process to form the desired functional bio-structures. Our approach reported here is an agent-based modeling method, which uses the kinetic Monte Carlo (KMC) algorithm to evolve the cellular system on a lattice. In this method, the cells and the hydrogel media, in which cells are embedded, are coarse-grained to material's points on a three-dimensional (3D) lattice, where the cell-cell and cell-medium interactions are quantified by adhesion and cohesion energies. In a multicellular aggregate system with a fixed number of cells and fixed amount of hydrogel media, where the effect of cell differentiation, proliferation and death are tactically neglected, the interaction energy is primarily dictated by the interfacial energy between cell and cell as well as between cell and medium particles on the lattice, respectively, based on the differential adhesion hypothesis. By using the transition state theory to track the time evolution of the multicellular system while minimizing the interfacial energy, KMC is shown to be an efficient time-dependent simulation tool to study the evolution of the multicellular aggregate system. In this study, numerical experiments are presented to simulate fusion and cell sorting during the biofabrication process of vascular networks, in which the bio-constructs are fabricated via engineering designs. The results predict the feasibility of fabricating the vascular structures

  15. Performance Analysis of Cluster Formation in Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Edgar Romo Montiel

    2017-12-01

    Full Text Available Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

  16. Performance Analysis of Cluster Formation in Wireless Sensor Networks.

    Science.gov (United States)

    Montiel, Edgar Romo; Rivero-Angeles, Mario E; Rubino, Gerardo; Molina-Lozano, Heron; Menchaca-Mendez, Rolando; Menchaca-Mendez, Ricardo

    2017-12-13

    Clustered-based wireless sensor networks have been extensively used in the literature in order to achieve considerable energy consumption reductions. However, two aspects of such systems have been largely overlooked. Namely, the transmission probability used during the cluster formation phase and the way in which cluster heads are selected. Both of these issues have an important impact on the performance of the system. For the former, it is common to consider that sensor nodes in a clustered-based Wireless Sensor Network (WSN) use a fixed transmission probability to send control data in order to build the clusters. However, due to the highly variable conditions experienced by these networks, a fixed transmission probability may lead to extra energy consumption. In view of this, three different transmission probability strategies are studied: optimal, fixed and adaptive. In this context, we also investigate cluster head selection schemes, specifically, we consider two intelligent schemes based on the fuzzy C-means and k-medoids algorithms and a random selection with no intelligence. We show that the use of intelligent schemes greatly improves the performance of the system, but their use entails higher complexity and selection delay. The main performance metrics considered in this work are energy consumption, successful transmission probability and cluster formation latency. As an additional feature of this work, we study the effect of errors in the wireless channel and the impact on the performance of the system under the different transmission probability schemes.

  17. Novel microspheres reduce the formation of deep venous thrombosis and repair the vascular wall in a rat model.

    Science.gov (United States)

    Dai, Bingyang; Li, Lan; Li, Qiangqiang; Song, Xiaoxiao; Chen, Dongyang; Dai, Jin; Yao, Yao; Yan, Wenjin; Teng, Huajian; Yang, Fang; Xu, Zhihong; Jiang, Qing

    2017-07-01

    : L-Arginine (L-arg), widely known as a substrate for endogenous nitric oxide synthesis, can improve endothelial function associated with the vasculature, inhibit platelet aggregation, and alter the activity of vascular smooth muscle cells. P-selectin is a membrane component of the platelet alpha-granule and the endothelial cell-specific Wiebel-Palade body that plays a central role in mediating interactions between platelets and both leukocytes and the endothelium. The experiment was designed to evaluate the effect of novel microspheres with L-arg targeting P-selectin on the formation of deep vein thrombosis and repair of vascular wall in a rat model. Thrombosis of the inferior vena cava was induced by applying a piece of filter paper (5 mm × 10 mm) saturated with 10% FeCl3 solution for 5 min. Targeted microspheres with L-arg, targeted microspheres with water, and saline were injected into the tail veins of the rats after 30 min of applying the filter paper saturated with 10% FeCl3 solution. The dry weight and length of the thrombus isolated from the inferior vena cava were significantly decreased in the group with L-arg in microsphere after 24 h. No significant differences in prothrombin time, activated partial thromboplastin time, thrombin time, and fibrinogen among the groups were indicated. Images revealed that apoptosis in the vascular wall was less in the group injected with targeted microspheres with L-arg than in the other two groups at 1 and 8 d postsurgery. Meanwhile, cell proliferation was considerably excessive in the group injected with L-arg wrapped in targeted microspheres. Therefore, these novel microspheres could decrease the formation of thrombus in the early stages and in the subsequent periods of thrombosis. The microspheres can also enhance the vitality of impaired endothelial cells and reduce cell apoptosis.

  18. PolNet: A Tool to Quantify Network-Level Cell Polarity and Blood Flow in Vascular Remodeling.

    Science.gov (United States)

    Bernabeu, Miguel O; Jones, Martin L; Nash, Rupert W; Pezzarossa, Anna; Coveney, Peter V; Gerhardt, Holger; Franco, Claudio A

    2018-05-08

    In this article, we present PolNet, an open-source software tool for the study of blood flow and cell-level biological activity during vessel morphogenesis. We provide an image acquisition, segmentation, and analysis protocol to quantify endothelial cell polarity in entire in vivo vascular networks. In combination, we use computational fluid dynamics to characterize the hemodynamics of the vascular networks under study. The tool enables, to our knowledge for the first time, a network-level analysis of polarity and flow for individual endothelial cells. To date, PolNet has proven invaluable for the study of endothelial cell polarization and migration during vascular patterning, as demonstrated by two recent publications. Additionally, the tool can be easily extended to correlate blood flow with other experimental observations at the cellular/molecular level. We release the source code of our tool under the Lesser General Public License. Copyright © 2018 Biophysical Society. Published by Elsevier Inc. All rights reserved.

  19. Domains I and IV of annexin A2 affect the formation and integrity of in vitro capillary-like networks.

    Directory of Open Access Journals (Sweden)

    Aase M Raddum

    Full Text Available Annexin A2 (AnxA2 is a widely expressed multifunctional protein found in different cellular compartments. In spite of lacking a hydrophobic signal peptide, AnxA2 is found at the cell surface of endothelial cells, indicative of a role in angiogenesis. Increased extracellular levels of AnxA2 in tumours correlate with neoangiogenesis, metastasis and poor prognosis. We hypothesised that extracellular AnxA2 may contribute to angiogenesis by affecting endothelial cell-cell interactions and motility. To address this question, we studied the effect of heterotetrameric and monomeric forms of AnxA2, as well as its two soluble domains on the formation and maintenance of capillary-like structures by using an in vitro co-culture system consisting of endothelial and smooth muscle cells. In particular, addition of purified domains I and IV of AnxA2 potently inhibited the vascular endothelial growth factor (VEGF-dependent formation of the capillary-like networks in a dose-dependent manner. In addition, these AnxA2 domains disrupted endothelial cell-cell contacts in preformed capillary-like networks, resulting in the internalisation of vascular endothelial (VE-cadherin and the formation of VE-cadherin-containing filopodia-like structures between the endothelial cells, suggesting increased cell motility. Addition of monoclonal AnxA2 antibodies, in particular against Tyr23 phosphorylated AnxA2, also strongly inhibited network formation in the co-culture system. These results suggest that extracellular AnxA2, most likely in its Tyr phosphorylated form, plays a pivotal role in angiogenesis. The exogenously added AnxA2 domains most likely mediate their effects by competing with endogenous AnxA2 for extracellular factors necessary for the initiation and maintenance of angiogenesis, such as those involved in the formation/integrity of cell-cell contacts.

  20. Adapted Boolean network models for extracellular matrix formation

    Directory of Open Access Journals (Sweden)

    Wollbold Johannes

    2009-07-01

    Full Text Available Abstract Background Due to the rapid data accumulation on pathogenesis and progression of chronic inflammation, there is an increasing demand for approaches to analyse the underlying regulatory networks. For example, rheumatoid arthritis (RA is a chronic inflammatory disease, characterised by joint destruction and perpetuated by activated synovial fibroblasts (SFB. These abnormally express and/or secrete pro-inflammatory cytokines, collagens causing joint fibrosis, or tissue-degrading enzymes resulting in destruction of the extra-cellular matrix (ECM. We applied three methods to analyse ECM regulation: data discretisation to filter out noise and to reduce complexity, Boolean network construction to implement logic relationships, and formal concept analysis (FCA for the formation of minimal, but complete rule sets from the data. Results First, we extracted literature information to develop an interaction network containing 18 genes representing ECM formation and destruction. Subsequently, we constructed an asynchronous Boolean network with biologically plausible time intervals for mRNA and protein production, secretion, and inactivation. Experimental gene expression data was obtained from SFB stimulated by TGFβ1 or by TNFα and discretised thereafter. The Boolean functions of the initial network were improved iteratively by the comparison of the simulation runs to the experimental data and by exploitation of expert knowledge. This resulted in adapted networks for both cytokine stimulation conditions. The simulations were further analysed by the attribute exploration algorithm of FCA, integrating the observed time series in a fine-tuned and automated manner. The resulting temporal rules yielded new contributions to controversially discussed aspects of fibroblast biology (e.g., considerable expression of TNF and MMP9 by fibroblasts stimulation and corroborated previously known facts (e.g., co-expression of collagens and MMPs after TNF

  1. Optical coherence tomography angiography indicates associations of the retinal vascular network and disease activity in multiple sclerosis.

    Science.gov (United States)

    Feucht, Nikolaus; Maier, Mathias; Lepennetier, Gildas; Pettenkofer, Moritz; Wetzlmair, Carmen; Daltrozzo, Tanja; Scherm, Pauline; Zimmer, Claus; Hoshi, Muna-Miriam; Hemmer, Bernhard; Korn, Thomas; Knier, Benjamin

    2018-01-01

    Patients with multiple sclerosis (MS) and clinically isolated syndrome (CIS) may show alterations of retinal layer architecture as measured by optical coherence tomography. Little is known about changes in the retinal vascular network during MS. To characterize retinal vessel structures in patients with MS and CIS and to test for associations with MS disease activity. In all, 42 patients with MS or CIS and 50 healthy controls underwent retinal optical coherence tomography angiography (OCT-A) with analysis of the superficial and deep vascular plexuses and the choriocapillaries. We tested OCT-A parameters for associations with retinal layer volumes, history of optic neuritis (ON), and the retrospective disease activity. Inner retinal layer volumes correlated positively with the density of both the superficial and deep vascular plexuses. Eyes of MS/CIS patients with a history of ON revealed reduced vessel densities of the superficial and deep vascular plexuses as compared to healthy controls. Higher choriocapillary vessel densities were associated with ongoing inflammatory disease activity during 24 months prior to OCT-A examination in MS and CIS patients. Optic neuritis is associated with rarefaction of the superficial and deep retinal vessels. Alterations of the choriocapillaries might be linked to disease activity in MS.

  2. Vascular niche promotes hematopoietic multipotent progenitor formation from pluripotent stem cells

    Science.gov (United States)

    Gori, Jennifer L.; Butler, Jason M.; Chan, Yan-Yi; Chandrasekaran, Devikha; Poulos, Michael G.; Ginsberg, Michael; Nolan, Daniel J.; Elemento, Olivier; Wood, Brent L.; Adair, Jennifer E.; Rafii, Shahin; Kiem, Hans-Peter

    2015-01-01

    Pluripotent stem cells (PSCs) represent an alternative hematopoietic stem cell (HSC) source for treating hematopoietic disease. The limited engraftment of human PSC–derived (hPSC-derived) multipotent progenitor cells (MPP) has hampered the clinical application of these cells and suggests that MPP require additional cues for definitive hematopoiesis. We hypothesized that the presence of a vascular niche that produces Notch ligands jagged-1 (JAG1) and delta-like ligand-4 (DLL4) drives definitive hematopoiesis. We differentiated hes2 human embryonic stem cells (hESC) and Macaca nemestrina–induced PSC (iPSC) line-7 with cytokines in the presence or absence of endothelial cells (ECs) that express JAG1 and DLL4. Cells cocultured with ECs generated substantially more CD34+CD45+ hematopoietic progenitors compared with cells cocultured without ECs or with ECs lacking JAG1 or DLL4. EC-induced cells exhibited Notch activation and expressed HSC-specific Notch targets RUNX1 and GATA2. EC-induced PSC-MPP engrafted at a markedly higher level in NOD/SCID/IL-2 receptor γ chain–null (NSG) mice compared with cytokine-induced cells, and low-dose chemotherapy-based selection further increased engraftment. Long-term engraftment and the myeloid-to-lymphoid ratio achieved with vascular niche induction were similar to levels achieved for cord blood–derived MPP and up to 20-fold higher than those achieved with hPSC-derived MPP engraftment. Our findings indicate that endothelial Notch ligands promote PSC-definitive hematopoiesis and production of long-term engrafting CD34+ cells, suggesting these ligands are critical for HSC emergence. PMID:25664855

  3. Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots

    KAUST Repository

    Muraro, D.

    2013-12-31

    As multicellular organisms grow, positional information is continually needed to regulate the pattern in which cells are arranged. In the Arabidopsis root, most cell types are organized in a radially symmetric pattern; however, a symmetry-breaking event generates bisymmetric auxin and cytokinin signaling domains in the stele. Bidirectional cross-talk between the stele and the surrounding tissues involving a mobile transcription factor, SHORT ROOT (SHR), and mobile microRNA species also determines vascular pattern, but it is currently unclear how these signals integrate. We use a multicellular model to determine a minimal set of components necessary for maintaining a stable vascular pattern. Simulations perturbing the signaling network show that, in addition to the mutually inhibitory interaction between auxin and cytokinin, signaling through SHR, microRNA165/6, and PHABULOSA is required to maintain a stable bisymmetric pattern. We have verified this prediction by observing loss of bisymmetry in shr mutants. The model reveals the importance of several features of the network, namely the mutual degradation of microRNA165/6 and PHABULOSA and the existence of an additional negative regulator of cytokinin signaling. These components form a plausible mechanism capable of patterning vascular tissues in the absence of positional inputs provided by the transport of hormones from the shoot.

  4. Integration of hormonal signaling networks and mobile microRNAs is required for vascular patterning in Arabidopsis roots

    KAUST Repository

    Muraro, D.; Mellor, N.; Pound, M. P.; Help, H.; Lucas, M.; Chopard, J.; Byrne, H. M.; Godin, C.; Hodgman, T. C.; King, J. R.; Pridmore, T. P.; Helariutta, Y.; Bennett, M. J.; Bishopp, A.

    2013-01-01

    As multicellular organisms grow, positional information is continually needed to regulate the pattern in which cells are arranged. In the Arabidopsis root, most cell types are organized in a radially symmetric pattern; however, a symmetry-breaking event generates bisymmetric auxin and cytokinin signaling domains in the stele. Bidirectional cross-talk between the stele and the surrounding tissues involving a mobile transcription factor, SHORT ROOT (SHR), and mobile microRNA species also determines vascular pattern, but it is currently unclear how these signals integrate. We use a multicellular model to determine a minimal set of components necessary for maintaining a stable vascular pattern. Simulations perturbing the signaling network show that, in addition to the mutually inhibitory interaction between auxin and cytokinin, signaling through SHR, microRNA165/6, and PHABULOSA is required to maintain a stable bisymmetric pattern. We have verified this prediction by observing loss of bisymmetry in shr mutants. The model reveals the importance of several features of the network, namely the mutual degradation of microRNA165/6 and PHABULOSA and the existence of an additional negative regulator of cytokinin signaling. These components form a plausible mechanism capable of patterning vascular tissues in the absence of positional inputs provided by the transport of hormones from the shoot.

  5. Notes on a PDE system for biological network formation

    KAUST Repository

    Haskovec, Jan

    2016-01-22

    We present new analytical and numerical results for the elliptic–parabolic system of partial differential equations proposed by Hu and Cai, which models the formation of biological transport networks. The model describes the pressure field using a Darcy’s type equation and the dynamics of the conductance network under pressure force effects. Randomness in the material structure is represented by a linear diffusion term and conductance relaxation by an algebraic decay term. The analytical part extends the results of Haskovec et al. (2015) regarding the existence of weak and mild solutions to the whole range of meaningful relaxation exponents. Moreover, we prove finite time extinction or break-down of solutions in the spatially one-dimensional setting for certain ranges of the relaxation exponent. We also construct stationary solutions for the case of vanishing diffusion and critical value of the relaxation exponent, using a variational formulation and a penalty method. The analytical part is complemented by extensive numerical simulations. We propose a discretization based on mixed finite elements and study the qualitative properties of network structures for various parameter values. Furthermore, we indicate numerically that some analytical results proved for the spatially one-dimensional setting are likely to be valid also in several space dimensions.

  6. Fractal Branching in Vascular Trees and Networks by VESsel GENeration Analysis (VESGEN)

    Science.gov (United States)

    Parsons-Wingerter, Patricia A.

    2016-01-01

    Vascular patterning offers an informative multi-scale, fractal readout of regulatory signaling by complex molecular pathways. Understanding such molecular crosstalk is important for physiological, pathological and therapeutic research in Space Biology and Astronaut countermeasures. When mapped out and quantified by NASA's innovative VESsel GENeration Analysis (VESGEN) software, remodeling vascular patterns become useful biomarkers that advance out understanding of the response of biology and human health to challenges such as microgravity and radiation in space environments.

  7. Prediction of Austenite Formation Temperatures Using Artificial Neural Networks

    International Nuclear Information System (INIS)

    Schulze, P; Schmidl, E; Grund, T; Lampke, T

    2016-01-01

    For the modeling and design of heat treatments, in consideration of the development/ transformation of the microstructure, different material data depending on the chemical composition, the respective microstructure/phases and the temperature are necessary. Material data are, e.g. the thermal conductivity, heat capacity, thermal expansion and transformation data etc. The quality of thermal simulations strongly depends on the accuracy of the material data. For many materials, the required data - in particular for different microstructures and temperatures - are rare in the literature. In addition, a different chemical composition within the permitted limits of the considered steel alloy cannot be predicted. A solution for this problem is provided by the calculation of material data using Artificial Neural Networks (ANN). In the present study, the start and finish temperatures of the transformation from the bcc lattice to the fcc lattice structure of hypoeutectoid steels are calculated using an Artificial Neural Network. An appropriate database containing different transformation temperatures (austenite formation temperatures) to train the ANN is selected from the literature. In order to find a suitable feedforward network, the network topologies as well as the activation functions of the hidden layers are varied and subsequently evaluated in terms of the prediction accuracy. The transformation temperatures calculated by the ANN exhibit a very good compliance compared to the experimental data. The results show that the prediction performance is even higher compared to classical empirical equations such as Andrews or Brandis. Therefore, it can be assumed that the presented ANN is a convenient tool to distinguish between bcc and fcc phases in hypoeutectoid steels. (paper)

  8. Prediction of Austenite Formation Temperatures Using Artificial Neural Networks

    Science.gov (United States)

    Schulze, P.; Schmidl, E.; Grund, T.; Lampke, T.

    2016-03-01

    For the modeling and design of heat treatments, in consideration of the development/ transformation of the microstructure, different material data depending on the chemical composition, the respective microstructure/phases and the temperature are necessary. Material data are, e.g. the thermal conductivity, heat capacity, thermal expansion and transformation data etc. The quality of thermal simulations strongly depends on the accuracy of the material data. For many materials, the required data - in particular for different microstructures and temperatures - are rare in the literature. In addition, a different chemical composition within the permitted limits of the considered steel alloy cannot be predicted. A solution for this problem is provided by the calculation of material data using Artificial Neural Networks (ANN). In the present study, the start and finish temperatures of the transformation from the bcc lattice to the fcc lattice structure of hypoeutectoid steels are calculated using an Artificial Neural Network. An appropriate database containing different transformation temperatures (austenite formation temperatures) to train the ANN is selected from the literature. In order to find a suitable feedforward network, the network topologies as well as the activation functions of the hidden layers are varied and subsequently evaluated in terms of the prediction accuracy. The transformation temperatures calculated by the ANN exhibit a very good compliance compared to the experimental data. The results show that the prediction performance is even higher compared to classical empirical equations such as Andrews or Brandis. Therefore, it can be assumed that the presented ANN is a convenient tool to distinguish between bcc and fcc phases in hypoeutectoid steels.

  9. Automatic modulation format recognition for the next generation optical communication networks using artificial neural networks

    Science.gov (United States)

    Guesmi, Latifa; Hraghi, Abir; Menif, Mourad

    2015-03-01

    A new technique for Automatic Modulation Format Recognition (AMFR) in next generation optical communication networks is presented. This technique uses the Artificial Neural Network (ANN) in conjunction with the features of Linear Optical Sampling (LOS) of the detected signal at high bit rates using direct detection or coherent detection. The use of LOS method for this purpose mainly driven by the increase of bit rates which enables the measurement of eye diagrams. The efficiency of this technique is demonstrated under different transmission impairments such as chromatic dispersion (CD) in the range of -500 to 500 ps/nm, differential group delay (DGD) in the range of 0-15 ps and the optical signal tonoise ratio (OSNR) in the range of 10-30 dB. The results of numerical simulation for various modulation formats demonstrate successful recognition from a known bit rates with a higher estimation accuracy, which exceeds 99.8%.

  10. MMP-sensitive PEG diacrylate hydrogels with spatial variations in matrix properties stimulate directional vascular sprout formation.

    Directory of Open Access Journals (Sweden)

    Michael V Turturro

    Full Text Available The spatial presentation of immobilized extracellular matrix (ECM cues and matrix mechanical properties play an important role in directed and guided cell behavior and neovascularization. The goal of this work was to explore whether gradients of elastic modulus, immobilized matrix metalloproteinase (MMP-sensitivity, and YRGDS cell adhesion ligands are capable of directing 3D vascular sprout formation in tissue engineered scaffolds. PEGDA hydrogels were engineered with mechanical and biofunctional gradients using perfusion-based frontal photopolymerization (PBFP. Bulk photopolymerized hydrogels with uniform mechanical properties, degradation, and immobilized biofunctionality served as controls. Gradient hydrogels exhibited an 80.4% decrease in elastic modulus and a 56.2% decrease in immobilized YRGDS. PBFP hydrogels also demonstrated gradients in hydrogel degradation with degradation times ranging from 10-12 hours in the more crosslinked regions to 4-6 hours in less crosslinked regions. An in vitro model of neovascularization, composed of co-culture aggregates of endothelial and smooth muscle cells, was used to evaluate the effect of these gradients on vascular sprout formation. Aggregate invasion in gradient hydrogels occurred bi-directionally with sprout alignment observed in the direction parallel to the gradient while control hydrogels with homogeneous properties resulted in uniform invasion. In PBFP gradient hydrogels, aggregate sprout length was found to be twice as long in the direction parallel to the gradient as compared to the perpendicular direction after three weeks in culture. This directionality was found to be more prominent in gradient regions of increased stiffness, crosslinked MMP-sensitive peptide presentation, and immobilized YRGDS concentration.

  11. It’s all about networking! Empirical investigation of social capital formation on social network sites

    OpenAIRE

    Koroleva, Ksenia; Krasnova, Hanna; Veltri, Natasha F.; Günther, Oliver

    2011-01-01

    As Social Network Sites (SNS) permeate our daily routines, the question whether participation results in value for SNS users becomes particularly acute. This study adopts a 'participation-source-outcome' perspective to explore how distinct uses of SNS generate various types of social capital benefits. Building on existing research, extensive qualitative findings and an empirical study with 253 Facebook users, we uncover the process of social capital formation on SNS. We find that even though ...

  12. Complement Activation Induces Neutrophil Adhesion and Neutrophil-Platelet Aggregate Formation on Vascular Endothelial Cells

    Directory of Open Access Journals (Sweden)

    Magdalena Riedl

    2017-01-01

    Discussion: Therefore, our findings of (i neutrophils adhering to complement-activated endothelial cells, (ii the formation of neutrophil-platelet aggregates on endothelial cells, and (iii the ability of aHUS serum to induce similar effects identify a possible role for neutrophils in aHUS manifestation.

  13. Toward Efficient Team Formation for Crowdsourcing in Noncooperative Social Networks.

    Science.gov (United States)

    Wang, Wanyuan; Jiang, Jiuchuan; An, Bo; Jiang, Yichuan; Chen, Bing

    2017-12-01

    Crowdsourcing has become a popular service computing paradigm for requesters to integrate the ubiquitous human-intelligence services for tasks that are difficult for computers but trivial for humans. This paper focuses on crowdsourcing complex tasks by team formation in social networks (SNs) where a requester connects to a large number of workers. A good indicator of efficient team collaboration is the social connection among workers. Most previous social team formation approaches, however, either assume that the requester can maintain information of all workers and can directly communicate with them to build teams, or assume that the workers are cooperative and be willing to join the specific team built by the requester, both of which are impractical in many real situations. To this end, this paper first models each worker as a selfish entity, where the requester prefers to hire inexpensive workers that require less payment and workers prefer to join the profitable teams where they can gain high revenue. Within the noncooperative SNs, a distributed negotiation-based team formation mechanism is designed for the requester to decide which worker to hire and for the worker to decide which team to join and how much should be paid for his skill service provision. The proposed social team formation approach can always build collaborative teams by allowing team members to form a connected graph such that they can work together efficiently. Finally, we conduct a set of experiments on real dataset of workers to evaluate the effectiveness of our approach. The experimental results show that our approach can: 1) preserve considerable social welfare by comparing the benchmark centralized approaches and 2) form the profitable teams within less negotiation time by comparing the traditional distributed approaches, making our approach a more economic option for real-world applications.

  14. Mean-field approach to evolving spatial networks, with an application to osteocyte network formation

    Science.gov (United States)

    Taylor-King, Jake P.; Basanta, David; Chapman, S. Jonathan; Porter, Mason A.

    2017-07-01

    We consider evolving networks in which each node can have various associated properties (a state) in addition to those that arise from network structure. For example, each node can have a spatial location and a velocity, or it can have some more abstract internal property that describes something like a social trait. Edges between nodes are created and destroyed, and new nodes enter the system. We introduce a "local state degree distribution" (LSDD) as the degree distribution at a particular point in state space. We then make a mean-field assumption and thereby derive an integro-partial differential equation that is satisfied by the LSDD. We perform numerical experiments and find good agreement between solutions of the integro-differential equation and the LSDD from stochastic simulations of the full model. To illustrate our theory, we apply it to a simple model for osteocyte network formation within bones, with a view to understanding changes that may take place during cancer. Our results suggest that increased rates of differentiation lead to higher densities of osteocytes, but with a smaller number of dendrites. To help provide biological context, we also include an introduction to osteocytes, the formation of osteocyte networks, and the role of osteocytes in bone metastasis.

  15. Deficiency of the NR4A Orphan Nuclear Receptor NOR1 attenuates Neointima Formation Following Vascular Injury

    Science.gov (United States)

    Nomiyama, Takashi; Zhao, Yue; Gizard, Florence; Findeisen, Hannes M.; Heywood, Elizabeth B.; Jones, Karrie L.; Conneely, Orla M.; Bruemmer, Dennis

    2009-01-01

    Background The neuron-derived orphan receptor-1 (NOR1) belongs to the evolutionary highly conserved and most ancient NR4A subfamily of the nuclear hormone receptor superfamily. Members of this subfamily function as early response genes regulating key cellular processes including proliferation, differentiation, and survival. Although NOR1 has previously been demonstrated to be required for smooth muscle cell (SMC) proliferation in vitro, the role of this nuclear receptor for the proliferative response underlying neointima formation and target genes trans-activated by NOR1 remain to be defined. Methods and Results Using a model of guide wire-induced arterial injury, we demonstrate decreased neointima formation in NOR1-/- mice compared to wildtype mice. In vitro, NOR1-deficient SMC exhibit decreased proliferation due to a G1→S phase arrest of the cell cycle and increased apoptosis in response to serum deprivation. NOR1-deficiency alters phosphorylation of the retinoblastoma protein by preventing mitogen-induced cyclin D1 and D2 expression. Conversely, overexpression of NOR1 induces cyclin D1 expression and the transcriptional activity of the cyclin D1 promoter in transient reporter assays. Gel shift and chromatin immunoprecipitation assays identified a putative response element for NR4A receptors in the cyclin D1 promoter, to which NOR1 is recruited in response to mitogenic stimulation. Finally, we provide evidence that these observations are applicable in vivo by demonstrating decreased cyclin D1 expression during neointima formation in NOR1-deficient mice. Conclusions These experiments characterize cyclin D1 as a NOR1-regulated target gene in SMC and demonstrate that NOR1 deficiency decreases neointima formation in response to vascular injury. PMID:19153266

  16. Bmp2 in osteoblasts of periosteum and trabecular bone links bone formation to vascularization and mesenchymal stem cells

    Science.gov (United States)

    Yang, Wuchen; Guo, Dayong; Harris, Marie A.; Cui, Yong; Gluhak-Heinrich, Jelica; Wu, Junjie; Chen, Xiao-Dong; Skinner, Charles; Nyman, Jeffry S.; Edwards, James R.; Mundy, Gregory R.; Lichtler, Alex; Kream, Barbara E.; Rowe, David W.; Kalajzic, Ivo; David, Val; Quarles, Darryl L.; Villareal, Demetri; Scott, Greg; Ray, Manas; Liu, S.; Martin, James F.; Mishina, Yuji; Harris, Stephen E.

    2013-01-01

    Summary We generated a new Bmp2 conditional-knockout allele without a neo cassette that removes the Bmp2 gene from osteoblasts (Bmp2-cKOob) using the 3.6Col1a1-Cre transgenic model. Bones of Bmp2-cKOob mice are thinner, with increased brittleness. Osteoblast activity is reduced as reflected in a reduced bone formation rate and failure to differentiate to a mature mineralizing stage. Bmp2 in osteoblasts also indirectly controls angiogenesis in the periosteum and bone marrow. VegfA production is reduced in Bmp2-cKOob osteoblasts. Deletion of Bmp2 in osteoblasts also leads to defective mesenchymal stem cells (MSCs), which correlates with the reduced microvascular bed in the periosteum and trabecular bones. Expression of several MSC marker genes (α-SMA, CD146 and Angiopoietin-1) in vivo, in vitro CFU assays and deletion of Bmp2 in vitro in α-SMA+ MSCs support our conclusions. Critical roles of Bmp2 in osteoblasts and MSCs are a vital link between bone formation, vascularization and mesenchymal stem cells. PMID:23843612

  17. 3,3'Diindolylmethane suppresses vascular smooth muscle cell phenotypic modulation and inhibits neointima formation after carotid injury.

    Directory of Open Access Journals (Sweden)

    Hongjing Guan

    Full Text Available 3,3'Diindolylmethane (DIM, a natural phytochemical, has shown inhibitory effects on the growth and migration of a variety of cancer cells; however, whether DIM has similar effects on vascular smooth muscle cells (VSMCs remains unknown. The purpose of this study was to assess the effects of DIM on the proliferation and migration of cultured VSMCs and neointima formation in a carotid injury model, as well as the related cell signaling mechanisms.DIM dose-dependently inhibited the platelet-derived growth factor (PDGF-BB-induced proliferation of VSMCs without cell cytotoxicity. This inhibition was caused by a G0/G1 phase cell cycle arrest demonstrated by fluorescence-activated cell-sorting analysis. We also showed that DIM-induced growth inhibition was associated with the inhibition of the expression of cyclin D1 and cyclin-dependent kinase (CDK 4/6 as well as an increase in p27(Kip1 levels in PDGF-stimulated VSMCs. Moreover, DIM was also found to modulate migration of VSMCs and smooth muscle-specific contractile marker expression. Mechanistically, DIM negatively modulated PDGF-BB-induced phosphorylation of PDGF-recptorβ (PDGF-Rβ and the activities of downstream signaling molecules including Akt/glycogen synthase kinase(GSK3β, extracellular signal-regulated kinase1/2 (ERK1/2, and signal transducers and activators of transcription 3 (STAT3. Our in vivo studies using a mouse carotid arterial injury model revealed that treatment with 150 mg/kg DIM resulted in significant reduction of the neointima/media ratio and proliferating cell nuclear antigen (PCNA-positive cells, without affecting apoptosis of vascular cells and reendothelialization. Infiltration of inflammatory cells was also inhibited by DIM administration.These results demonstrate that DIM can suppress the phenotypic modulation of VSMCs and neointima hyperplasia after vascular injury. These beneficial effects on VSMCs were at least partly mediated by the inhibition of PDGF-Rβ and the

  18. Simulating the formation of keratin filament networks by a piecewise-deterministic Markov process.

    Science.gov (United States)

    Beil, Michael; Lück, Sebastian; Fleischer, Frank; Portet, Stéphanie; Arendt, Wolfgang; Schmidt, Volker

    2009-02-21

    Keratin intermediate filament networks are part of the cytoskeleton in epithelial cells. They were found to regulate viscoelastic properties and motility of cancer cells. Due to unique biochemical properties of keratin polymers, the knowledge of the mechanisms controlling keratin network formation is incomplete. A combination of deterministic and stochastic modeling techniques can be a valuable source of information since they can describe known mechanisms of network evolution while reflecting the uncertainty with respect to a variety of molecular events. We applied the concept of piecewise-deterministic Markov processes to the modeling of keratin network formation with high spatiotemporal resolution. The deterministic component describes the diffusion-driven evolution of a pool of soluble keratin filament precursors fueling various network formation processes. Instants of network formation events are determined by a stochastic point process on the time axis. A probability distribution controlled by model parameters exercises control over the frequency of different mechanisms of network formation to be triggered. Locations of the network formation events are assigned dependent on the spatial distribution of the soluble pool of filament precursors. Based on this modeling approach, simulation studies revealed that the architecture of keratin networks mostly depends on the balance between filament elongation and branching processes. The spatial distribution of network mesh size, which strongly influences the mechanical characteristics of filament networks, is modulated by lateral annealing processes. This mechanism which is a specific feature of intermediate filament networks appears to be a major and fast regulator of cell mechanics.

  19. Effect of in situ hypothermic perfusion on intrahepatic pO(2) and reactive oxygen species formation after partial hepatectomy under total hepatic vascular exclusion in pigs

    NARCIS (Netherlands)

    Heijnen, Bob H. M.; Straatsburg, Irene H.; Kager, Liesbeth M.; van der Kleij, Ad J.; Gouma, Dirk J.; van Gulik, Thomas M.

    2003-01-01

    Aim: This study examined attenuation of ischemia and reperfusion (I/R) induced liver injury during liver resections by hypothermic perfusion of the liver under total hepatic vascular exclusion (THVE). Method: Reactive oxygen species (ROS) formation, microcirculatory integrity and endothelial cell

  20. Identification of cyst nematode B-type CLE peptides and modulation of the vascular stem cell pathway for feeding cell formation

    Science.gov (United States)

    Stem cells are important in the continuous formation of various tissues during postembryonic organogenesis. Stem cell pools in the SAM (shoot apical meristem), RAM (root apical meristem) and vascular procambium/cambium are regulated by CLE-receptor kinase-WOX signaling modules. Previous data showed ...

  1. Shear-Induced Amyloid Formation in the Brain: I. Potential Vascular and Parenchymal Processes.

    Science.gov (United States)

    Trumbore, Conrad N

    2016-09-06

    Shear distortion of amyloid-beta (Aβ) solutions accelerates amyloid cascade reactions that may yield different toxic oligomers than those formed in quiescent solutions. Recent experiments indicate that cerebrospinal fluid (CSF) and interstitial fluid (ISF) containing Aβ flow through narrow brain perivascular pathways and brain parenchyma. This paper suggests that such flow causes shear distortion of Aβ molecules involving conformation changes that may be one of the initiating events in the etiology of Alzheimer's disease. Aβ shearing can occur in or around brain arteries and arterioles and is suggested as the origin of cerebral amyloid angiopathy deposits in cerebrovascular walls. Comparatively low flow rates of ISF within the narrow extracellular spaces (ECS) of the brain parenchyma are suggested as a possible initiating factor in both the formation of neurotoxic Aβ42 oligomers and amyloid fibrils. Aβ42 in slow-flowing ISF can gain significant shear energy at or near the walls of tortuous brain ECS flow paths, promoting the formation of a shear-distorted, excited state hydrophobic Aβ42* conformation. This Aβ42* molecule could possibly be involved in one of two paths, one involving rapid adsorption to a brain membrane surface, ultimately forming neurotoxic oligomers on membranes, and the other ultimately forming plaque within the ECS flow pathways. Rising Aβ concentrations combined with shear at or near critical brain membranes are proposed as contributing factors to Alzheimer's disease neurotoxicity. These hypotheses may be applicable in other neurodegenerative diseases, including tauopathies and alpha-synucleinopathies, in which shear-distorted proteins also may form in the brain ECS.

  2. Opinion formation models in static and dynamic social networks

    Science.gov (United States)

    Singh, Pramesh

    We study models of opinion formation on static as well as dynamic networks where interaction among individuals is governed by widely accepted social theories. In particular, three models of competing opinions based on distinct interaction mechanisms are studied. A common feature in all of these models is the existence of a tipping point in terms of a model parameter beyond which a rapid consensus is reached. In the first model that we study on a static network, a node adopts a particular state (opinion) if a threshold fraction of its neighbors are already in that state. We introduce a few initiator nodes which are in state '1' in a population where every node is in state '0'. Thus, opinion '1' spreads through the population until no further influence is possible. Size of the spread is greatly affected by how these initiator nodes are selected. We find that there exists a critical fraction of initiators pc that is needed to trigger global cascades for a given threshold phi. We also study heuristic strategies for selecting a set of initiator nodes in order to maximize the cascade size. The structural properties of networks also play an important role in the spreading process. We study how the dynamics is affected by changing the clustering in a network. It turns out that local clustering is helpful in spreading. Next, we studied a model where the network is dynamic and interactions are homophilic. We find that homophily-driven rewiring impedes the reaching of consensus and in the absence of committed nodes (nodes that are not influenceable on their opinion), consensus time Tc diverges exponentially with network size N . As we introduce a fraction of committed nodes, beyond a critical value, the scaling of Tc becomes logarithmic in N. We also find that slight change in the interaction rule can produce strikingly different scaling behaviors of T c . However, introducing committed agents in the system drastically improves the scaling of the consensus time regardless of

  3. Biomaterials with persistent growth factor gradients in vivo accelerate vascularized tissue formation.

    Science.gov (United States)

    Akar, Banu; Jiang, Bin; Somo, Sami I; Appel, Alyssa A; Larson, Jeffery C; Tichauer, Kenneth M; Brey, Eric M

    2015-12-01

    Gradients of soluble factors play an important role in many biological processes, including blood vessel assembly. Gradients can be studied in detail in vitro, but methods that enable the study of spatially distributed soluble factors and multi-cellular processes in vivo are limited. Here, we report on a method for the generation of persistent in vivo gradients of growth factors in a three-dimensional (3D) biomaterial system. Fibrin loaded porous poly (ethylene glycol) (PEG) scaffolds were generated using a particulate leaching method. Platelet derived growth factor BB (PDGF-BB) was encapsulated into poly (lactic-co-glycolic acid) (PLGA) microspheres which were placed distal to the tissue-material interface. PLGA provides sustained release of PDGF-BB and its diffusion through the porous structure results in gradient formation. Gradients within the scaffold were confirmed in vivo using near-infrared fluorescence imaging and gradients were present for more than 3 weeks. The diffusion of PDGF-BB was modeled and verified with in vivo imaging findings. The depth of tissue invasion and density of blood vessels formed in response to the biomaterial increased with magnitude of the gradient. This biomaterial system allows for generation of sustained growth factor gradients for the study of tissue response to gradients in vivo. Published by Elsevier Ltd.

  4. Linear approximation model network and its formation via ...

    Indian Academy of Sciences (India)

    To overcome the deficiency of `local model network' (LMN) techniques, an alternative `linear approximation model' (LAM) network approach is proposed. Such a network models a nonlinear or practical system with multiple linear models fitted along operating trajectories, where individual models are simply networked ...

  5. Vascular Adaptation: Pattern Formation and Cross Validation between an Agent Based Model and a Dynamical System.

    Science.gov (United States)

    Garbey, Marc; Casarin, Stefano; Berceli, Scott A

    2017-09-21

    Myocardial infarction is the global leading cause of mortality (Go et al., 2014). Coronary artery occlusion is its main etiology and it is commonly treated by Coronary Artery Bypass Graft (CABG) surgery (Wilson et al, 2007). The long-term outcome remains unsatisfactory (Benedetto, 2016) as the graft faces the phenomenon of restenosis during the post-surgery, which consists of re-occlusion of the lumen and usually requires secondary intervention even within one year after the initial surgery (Harskamp, 2013). In this work, we propose an extensive study of the restenosis phenomenon by implementing two mathematical models previously developed by our group: a heuristic Dynamical System (DS) (Garbey and Berceli, 2013), and a stochastic Agent Based Model (ABM) (Garbey et al., 2015). With an extensive use of the ABM, we retrieved the pattern formations of the cellular events that mainly lead the restenosis, especially focusing on mitosis in intima, caused by alteration in shear stress, and mitosis in media, fostered by alteration in wall tension. A deep understanding of the elements at the base of the restenosis is indeed crucial in order to improve the final outcome of vein graft bypass. We also turned the ABM closer to the physiological reality by abating its original assumption of circumferential symmetry. This allowed us to finely replicate the trigger event of the restenosis, i.e. the loss of the endothelium in the early stage of the post-surgical follow up (Roubos et al., 1995) and to simulate the encroachment of the lumen in a fashion aligned with histological evidences (Owens et al., 2015). Finally, we cross-validated the two models by creating an accurate matching procedure. In this way we added the degree of accuracy given by the ABM to a simplified model (DS) that can serve as powerful predictive tool for the clinic. Copyright © 2017 Elsevier Ltd. All rights reserved.

  6. Printing continuously graded interpenetrating polymer networks of acrylate/epoxy by manipulating cationic network formation during stereolithography

    Directory of Open Access Journals (Sweden)

    W. Li

    2016-12-01

    Full Text Available Ultra-violet (UV laser assisted stereolithography is used to print graded interpenetrating polymer networks (IPNs by controlling network formation. Unlike the traditional process where structural change in IPNs is achieved by varying the feeding ratio of monomers or polymer precursors, in this demonstration property is changed by controlled termination of network formation. A photo-initiated process is used to construct IPNs by a combination of radical and cationic network formation in an acrylate/epoxy system. The extent of the cationic network formation is used to control the final properties of the system. Rapid-Scan Fourier Transformation Infrared Spectroscopy (RS-FTIR is used to track the curing kinetics of the two networks and identify key parameters to control the final properties. Atomic force microscopy (AFM and differential scanning calorimetry (DSC confirm the formation of homogenous IPNs, whereas nano-indentation indicates that properties vary with the extent of cationic network formation. The curing characteristics are used to design and demonstrate printing of graded IPNs that show two orders of magnitude variation in mechanical properties in the millimeter scale.

  7. 3D printed scaffolds of calcium silicate-doped β-TCP synergize with co-cultured endothelial and stromal cells to promote vascularization and bone formation.

    Science.gov (United States)

    Deng, Yuan; Jiang, Chuan; Li, Cuidi; Li, Tao; Peng, Mingzheng; Wang, Jinwu; Dai, Kerong

    2017-07-17

    Synthetic bone scaffolds have potential application in repairing large bone defects, however, inefficient vascularization after implantation remains the major issue of graft failure. Herein, porous β-tricalcium phosphate (β-TCP) scaffolds with calcium silicate (CS) were 3D printed, and pre-seeded with co-cultured human umbilical cord vein endothelial cells (HUVECs) and human bone marrow stromal cells (hBMSCs) to construct tissue engineering scaffolds with accelerated vascularization and better bone formation. Results showed that in vitro β-TCP scaffolds doped with 5% CS (5%CS/β-TCP) were biocompatible, and stimulated angiogenesis and osteogenesis. The results also showed that 5%CS/β-TCP scaffolds not only stimulated co-cultured cells angiogenesis on Matrigel, but also stimulated co-cultured cells to form microcapillary-like structures on scaffolds, and promoted migration of BMSCs by stimulating co-cultured cells to secrete PDGF-BB and CXCL12 into the surrounding environment. Moreover, 5%CS/β-TCP scaffolds enhanced vascularization and osteoinduction in comparison with β-TCP, and synergized with co-cultured cells to further increase early vessel formation, which was accompanied by earlier and better ectopic bone formation when implanted subcutaneously in nude mice. Thus, our findings suggest that porous 5%CS/β-TCP scaffolds seeded with co-cultured cells provide new strategy for accelerating tissue engineering scaffolds vascularization and osteogenesis, and show potential as treatment for large bone defects.

  8. Time course of fibronectin in the peri-implant tissue and neointima formation after functional implantation of polyester-based vascular prostheses with different porosity in pigs

    Energy Technology Data Exchange (ETDEWEB)

    Patrzyk, Maciej; Hoene, Andreas [Department of Surgery, Ernst Moritz Arndt University Greifswald, Friedrich-Loeffler-Str. 23, D-17489 Greifswald (Germany); Jarchow, Raymond [Computation Centre, Ernst Moritz Arndt University Greifswald, Felix-Hausdorff-Str. 12, D-17489 Greifswald (Germany); Wilhelm, Lutz [Department of Surgery, Hospital Demmin, Loitzer Str. 1, D-17109 Demmin (Germany); Walschus, Uwe; Schlosser, Michael [Research Group of Predictive Diagnostics of the Department of Medical Biochemistry and Molecular Biology and Institute of Pathophysiology, Ernst Moritz Arndt University Greifswald, Greifswalder Str. 11c, D-17495 Karlsburg (Germany); Zippel, Roland, E-mail: schlosse@uni-greifswald.d [Department of Surgery, Elbland Hospital Center, Weinbergstr. 8, D-01589 Riesa (Germany)

    2010-10-01

    Intima hyperplasia, resulting from extracellular matrix (ECM) secretion, can lead to vascular prosthesis occlusion and is a major problem in vascular surgery. Fibronectin might contribute to ongoing ECM secretion. However, the exact role of fibronectin and its influence on neointima formation remains unclear. This study was aimed at investigating the time course of the fibronectin area fraction and neointima formation following the functional implantation of three different polyester vascular prostheses into pigs. The infrarenal aorta from 15 animals (n = 5/group) was replaced by prosthesis segments with low, medium and high primary porosity. After 7, 14, 21, 28 and 116 days, the prostheses were morphometrically examined. Overall, the fibronectin area fraction was inversely correlated with the neointima thickness, demonstrating high fibronectin levels in the early phase (days 7 and 14) and low levels in the later phase with almost complete neointima formation (days 21-116). Throughout the study, fibronectin levels were highest at the proximal anastomosis region. The low porosity prosthesis had the highest fibronectin area fraction and a delayed neointima formation in the middle phase (days 21 and 28) but the highest neointima lining on day 116. The results indicate a relationship between fibronectin and neointima formation with the prosthesis porosity, demonstrating the importance of the textile design for tissue reactions following implantation.

  9. Effects of Electroacupuncture on Learning, Memory and Formation System of Free Radicals in Brain Tissues of Vascular Dementia Model Rats

    Institute of Scientific and Technical Information of China (English)

    王黎; 唐纯志; 赖新生

    2004-01-01

    In order to observe the regulative effect of electro-acupuncture on the formation system of free radicals in the brain tissues and learning and memory in vascular dementia (VD) model rats, the Morris's water labyrinth was used for testing the learning ability and memory in VD model rats made by 4-vessel occlusion method, and the activities or contents of nitric oxide (NO), NO synthase (NOS), superoxide dismutase (SOD), malondialdehyde (MDA), glutathione peroxidase (GSH-Px) were determined. Results showed that the mean escape latency in the electro-acupuncture group was markedly reduced in place test, and the times swam the place of the plate-form in the original plate-form quadrant were significantly more than those in the rest three quadrants in spatia1 probe test as compared with the model group. In the electro-acupuncture group and the nimodipine group the contents of NO and MDA and the activity of NOS were decreased, while the activities of SOD and GSH-Px were increased. It is indicated that electro-acupuncture can modulate the production and clearance of free radicals, and improve the ability of learning and memory of the VD model rats.

  10. Linear approximation model network and its formation via ...

    Indian Academy of Sciences (India)

    niques, an alternative `linear approximation model' (LAM) network approach is .... network is LPV, existing LTI theory is difficult to apply (Kailath 1980). ..... Beck J V, Arnold K J 1977 Parameter estimation in engineering and science (New York: ...

  11. Small GTP-Binding Protein Rac Is an Essential Mediator of Vascular Endothelial Growth Factor-Induced Endothelial Fenestrations and Vascular Permeability

    DEFF Research Database (Denmark)

    Eriksson, A.; Cao, R.; Tritsaris, K.

    2003-01-01

    fenestrated endothelium, a feature linked with increased vascular permeability. A cell-permeable Rac antagonist (TAT-RacN17) converted VEGF-induced, leaky vascular plexuses into well-defined vascular networks. In addition, this Rac mutant blocked formation of VEGF-induced endothelial fenestrations...... in mediation of VEGF-induced vascular permeability but less so in neovascularization. This may have conceptual implications for applying Rac antagonists in treatment and prevention of VEGF-induced vascular leakage and edema in connection with ischemic disorders....

  12. The formation of a core-periphery structure in heterogeneous financial networks

    NARCIS (Netherlands)

    van der Leij, M.; in 't Veld, D.; Hommes, C.

    2016-01-01

    Recent empirical evidence suggests that financial networks exhibit a core-periphery network structure. This paper aims at giving an explanation for the emergence of such a structure using network formation theory. We propose a simple model of the overnight interbank lending market, in which banks

  13. A review of mathematical models for the formation of vascular networks

    KAUST Repository

    Scianna, M.; Bell, C.G.; Preziosi, L.

    2013-01-01

    process generally called lymphangiogenesis. A number of mathematical approaches have been used to analyze these phenomena. In this paper, we review the different types of models, with special emphasis on their ability to reproduce different biological

  14. Vascular networks due to dynamically arrested crystalline ordering of elongated cells

    NARCIS (Netherlands)

    M.M. Palm (Margriet); R.M.H. Merks (Roeland)

    2013-01-01

    htmlabstractRecent experimental and theoretical studies suggest that crystallization and glass-like solidification are useful analogies for understanding cell ordering in confluent biological tissues. It remains unexplored how cellular ordering contributes to pattern formation during morphogenesis.

  15. Vascular networks due to dynamically arrested crystalline ordering of elongated cells

    NARCIS (Netherlands)

    M.M. Palm (Margriet); R.M.H. Merks (Roeland)

    2012-01-01

    htmlabstractRecent experimental and theoretical studies suggest that crystallization and glass-like solidification are useful analogies for understanding cell ordering in confluent biological tissues. It remains unexplored how cellular ordering contributes to pattern formation during morphogenesis.

  16. Detection and three-dimensional reconstruction of a vascular network from serial sections

    Energy Technology Data Exchange (ETDEWEB)

    Ip, H H.S.

    1983-07-01

    The process of three-dimensional reconstruction from serial sections includes aligning adjacent sections, segmenting the desired objects and constructing a computer internal model of the reconstructed object. Computational methodologies taking advantage of the parallel processing facilities of CLIP4 are presented for automating these tasks. The author is interested in the detailed structure of the carotid body which is a highly vascularized organ with the largest blood flow rate of any tissue in the body (Biscoe (1971), Seidl (1975), Lubbers et al. (1977), Clarke and Daly (1982)). It plays an important role in monitoring the chemical composition of arterial blood (p(o/sub 2/), p(co/sub 2/), ph). The aim of the investigation in the paper is to reconstruct the total vasculature of the organ and to make an analytical study of the geometrical configuration of its vessels. 15 references.

  17. Modulation of VEGF-induced migration and network formation by lymphatic endothelial cells: Roles of platelets and podoplanin.

    Science.gov (United States)

    Langan, Stacey A; Navarro-Núñez, Leyre; Watson, Steve P; Nash, Gerard B

    2017-07-20

    Lymphatic endothelial cells (LEC) express the transmembrane receptor podoplanin whose only known endogenous ligand CLEC-2 is found on platelets. Both podoplanin and CLEC-2 are required for normal lymphangiogenesis as mice lacking either protein develop a blood-lymphatic mixing phenotype. We investigated the roles of podoplanin and its interaction with platelets in migration and tube formation by LEC. Addition of platelets or antibody-mediated crosslinking of podoplanin inhibited LEC migration induced by vascular endothelial growth factors (VEGF-A or VEGF-C), but did not modify basal migration or the response to basic fibroblast growth factor or epidermal growth factor. In addition, platelets and podoplanin crosslinking disrupted networks of LEC formed in co-culture with fibroblasts. Depletion of podoplanin in LEC using siRNA negated the pro-migratory effect of VEGF-A and VEGF-C. Inhibition of RhoA or Rho-kinase reduced LEC migration induced by VEGF-C, but had no further effect after crosslinking of podoplanin, suggesting that podoplanin is required for signaling downstream of VEGF-receptors but upstream of RhoA. Together, these data reveal for the first time that podoplanin is an intrinsic specific regulator of VEGF-mediated migration and network formation in LEC and identify crosslinking of podoplanin by platelets or antibodies as mechanisms to modulate this pathway.

  18. Pattern formation and firing synchronization in networks of map neurons

    International Nuclear Information System (INIS)

    Wang Qingyun; Duan Zhisheng; Huang Lin; Chen Guanrong; Lu Qishao

    2007-01-01

    Patterns and collective phenomena such as firing synchronization are studied in networks of nonhomogeneous oscillatory neurons and mixtures of oscillatory and excitable neurons, with dynamics of each neuron described by a two-dimensional (2D) Rulkov map neuron. It is shown that as the coupling strength is increased, typical patterns emerge spatially, which propagate through the networks in the form of beautiful target waves or parallel ones depending on the size of networks. Furthermore, we investigate the transitions of firing synchronization characterized by the rate of firing when the coupling strength is increased. It is found that there exists an intermediate coupling strength; firing synchronization is minimal simultaneously irrespective of the size of networks. For further increasing the coupling strength, synchronization is enhanced. Since noise is inevitable in real neurons, we also investigate the effects of white noise on firing synchronization for different networks. For the networks of oscillatory neurons, it is shown that firing synchronization decreases when the noise level increases. For the missed networks, firing synchronization is robust under the noise conditions considered in this paper. Results presented in this paper should prove to be valuable for understanding the properties of collective dynamics in real neuronal networks

  19. Dll4-Notch signaling determines the formation of native arterial collateral networks and arterial function in mouse ischemia models.

    Science.gov (United States)

    Cristofaro, Brunella; Shi, Yu; Faria, Marcella; Suchting, Steven; Leroyer, Aurelie S; Trindade, Alexandre; Duarte, Antonio; Zovein, Ann C; Iruela-Arispe, M Luisa; Nih, Lina R; Kubis, Nathalie; Henrion, Daniel; Loufrani, Laurent; Todiras, Mihail; Schleifenbaum, Johanna; Gollasch, Maik; Zhuang, Zhen W; Simons, Michael; Eichmann, Anne; le Noble, Ferdinand

    2013-04-01

    Arteriogenesis requires growth of pre-existing arteriolar collateral networks and determines clinical outcome in arterial occlusive diseases. Factors responsible for the development of arteriolar collateral networks are poorly understood. The Notch ligand Delta-like 4 (Dll4) promotes arterial differentiation and restricts vessel branching. We hypothesized that Dll4 may act as a genetic determinant of collateral arterial networks and functional recovery in stroke and hind limb ischemia models in mice. Genetic loss- and gain-of-function approaches in mice showed that Dll4-Notch signaling restricts pial collateral artery formation by modulating arterial branching morphogenesis during embryogenesis. Adult Dll4(+/-) mice showed increased pial collateral numbers, but stroke volume upon middle cerebral artery occlusion was not reduced compared with wild-type littermates. Likewise, Dll4(+/-) mice showed reduced blood flow conductance after femoral artery occlusion, and, despite markedly increased angiogenesis, tissue ischemia was more severe. In peripheral arteries, loss of Dll4 adversely affected excitation-contraction coupling in arterial smooth muscle in response to vasopressor agents and arterial vessel wall adaption in response to increases in blood flow, collectively contributing to reduced flow reserve. We conclude that Dll4-Notch signaling modulates native collateral formation by acting on vascular branching morphogenesis during embryogenesis. Dll4 furthermore affects tissue perfusion by acting on arterial function and structure. Loss of Dll4 stimulates collateral formation and angiogenesis, but in the context of ischemic diseases such beneficial effects are overruled by adverse functional changes, demonstrating that ischemic recovery is not solely determined by collateral number but rather by vessel functionality.

  20. Dll4-Notch signaling determines the formation of native arterial collateral networks and arterial function in mouse ischemia models

    Science.gov (United States)

    Cristofaro, Brunella; Shi, Yu; Faria, Marcella; Suchting, Steven; Leroyer, Aurelie S.; Trindade, Alexandre; Duarte, Antonio; Zovein, Ann C.; Iruela-Arispe, M. Luisa; Nih, Lina R.; Kubis, Nathalie; Henrion, Daniel; Loufrani, Laurent; Todiras, Mihail; Schleifenbaum, Johanna; Gollasch, Maik; Zhuang, Zhen W.; Simons, Michael; Eichmann, Anne; le Noble, Ferdinand

    2013-01-01

    Arteriogenesis requires growth of pre-existing arteriolar collateral networks and determines clinical outcome in arterial occlusive diseases. Factors responsible for the development of arteriolar collateral networks are poorly understood. The Notch ligand Delta-like 4 (Dll4) promotes arterial differentiation and restricts vessel branching. We hypothesized that Dll4 may act as a genetic determinant of collateral arterial networks and functional recovery in stroke and hind limb ischemia models in mice. Genetic loss- and gain-of-function approaches in mice showed that Dll4-Notch signaling restricts pial collateral artery formation by modulating arterial branching morphogenesis during embryogenesis. Adult Dll4+/- mice showed increased pial collateral numbers, but stroke volume upon middle cerebral artery occlusion was not reduced compared with wild-type littermates. Likewise, Dll4+/- mice showed reduced blood flow conductance after femoral artery occlusion, and, despite markedly increased angiogenesis, tissue ischemia was more severe. In peripheral arteries, loss of Dll4 adversely affected excitation-contraction coupling in arterial smooth muscle in response to vasopressor agents and arterial vessel wall adaption in response to increases in blood flow, collectively contributing to reduced flow reserve. We conclude that Dll4-Notch signaling modulates native collateral formation by acting on vascular branching morphogenesis during embryogenesis. Dll4 furthermore affects tissue perfusion by acting on arterial function and structure. Loss of Dll4 stimulates collateral formation and angiogenesis, but in the context of ischemic diseases such beneficial effects are overruled by adverse functional changes, demonstrating that ischemic recovery is not solely determined by collateral number but rather by vessel functionality. PMID:23533173

  1. Strategies in interventional radiology. Formation of an interdisciplinary center of vascular anomalies. Chances and challenges for effective and efficient patient management; Strategien in der interventionellen Radiologie. Gruendung eines Interdisziplinaeres Zentrum fuer Gefaessanomalien. Chancen und Herausforderungen fuer effektives und effizientes Patientenmanagement

    Energy Technology Data Exchange (ETDEWEB)

    Sadick, Maliha; Dally, Franz Josef; Schoenberg, Stefan O. [University Medical Center Mannheim (Germany). Interdisciplinary Center for Vascular Anomalies; Stroszczynski, Christian [University Hospital Regensburg (Germany). Dept. of Radiology; Wohlgemuth, Walter A. [University Hospital Halle (Germany). Interdisciplinary Center for Vascular Anomalies

    2017-10-15

    Radiology is an interdisciplinary field dedicated to the diagnosis and treatment of numerous diseases and is involved in the development of multimodal treatment concepts. Interdisciplinary case management, a broad spectrum of diagnostic imaging facilities and dedicated endovascular radiological treatment options are valuable tools that allow radiology to set up an interdisciplinary center for vascular anomalies. Image-based diagnosis combined with endovascular treatment options is an essential tool for the treatment of patients with highly complex vascular diseases. These vascular anomalies can affect numerous parts of the body so that a multidisciplinary treatment approach is required for optimal patient care. This paper discusses the possibilities and challenges regarding effective and efficient patient management in connection with the formation of an interdisciplinary center for vascular anomalies with strengthening of the clinical role of radiologists. Key points: Vascular anomalies, which include vascular tumors and malformations, are complex to diagnose and treat. There are far more patients with vascular anomalies requiring therapy than interdisciplinary centers for vascular anomalies - there is currently a shortage of dedicated interdisciplinary centers for vascular anomalies in Germany that can provide dedicated care for affected patients. Radiology includes a broad spectrum of diagnostic and minimally invasive therapeutic tools which allow the formation of an interdisciplinary center for vascular anomalies for effective, efficient and comprehensive patient management.

  2. Bioprinting for vascular and vascularized tissue biofabrication.

    Science.gov (United States)

    Datta, Pallab; Ayan, Bugra; Ozbolat, Ibrahim T

    2017-03-15

    Bioprinting is a promising technology to fabricate design-specific tissue constructs due to its ability to create complex, heterocellular structures with anatomical precision. Bioprinting enables the deposition of various biologics including growth factors, cells, genes, neo-tissues and extra-cellular matrix-like hydrogels. Benefits of bioprinting have started to make a mark in the fields of tissue engineering, regenerative medicine and pharmaceutics. Specifically, in the field of tissue engineering, the creation of vascularized tissue constructs has remained a principal challenge till date. However, given the myriad advantages over other biofabrication methods, it becomes organic to expect that bioprinting can provide a viable solution for the vascularization problem, and facilitate the clinical translation of tissue engineered constructs. This article provides a comprehensive account of bioprinting of vascular and vascularized tissue constructs. The review is structured as introducing the scope of bioprinting in tissue engineering applications, key vascular anatomical features and then a thorough coverage of 3D bioprinting using extrusion-, droplet- and laser-based bioprinting for fabrication of vascular tissue constructs. The review then provides the reader with the use of bioprinting for obtaining thick vascularized tissues using sacrificial bioink materials. Current challenges are discussed, a comparative evaluation of different bioprinting modalities is presented and future prospects are provided to the reader. Biofabrication of living tissues and organs at the clinically-relevant volumes vitally depends on the integration of vascular network. Despite the great progress in traditional biofabrication approaches, building perfusable hierarchical vascular network is a major challenge. Bioprinting is an emerging technology to fabricate design-specific tissue constructs due to its ability to create complex, heterocellular structures with anatomical precision

  3. Spontaneous formation of dynamical groups in an adaptive networked system

    International Nuclear Information System (INIS)

    Li Menghui; Guan Shuguang; Lai, C-H

    2010-01-01

    In this work, we investigate a model of an adaptive networked dynamical system, where the coupling strengths among phase oscillators coevolve with the phase states. It is shown that in this model the oscillators can spontaneously differentiate into two dynamical groups after a long time evolution. Within each group, the oscillators have similar phases, while oscillators in different groups have approximately opposite phases. The network gradually converts from the initial random structure with a uniform distribution of connection strengths into a modular structure that is characterized by strong intra-connections and weak inter-connections. Furthermore, the connection strengths follow a power-law distribution, which is a natural consequence of the coevolution of the network and the dynamics. Interestingly, it is found that if the inter-connections are weaker than a certain threshold, the two dynamical groups will almost decouple and evolve independently. These results are helpful in further understanding the empirical observations in many social and biological networks.

  4. Notes on a PDE system for biological network formation

    KAUST Repository

    Haskovec, Jan; Markowich, Peter A.; Perthame, Benoî t; Schlottbom, Matthias

    2016-01-01

    Darcy’s type equation and the dynamics of the conductance network under pressure force effects. Randomness in the material structure is represented by a linear diffusion term and conductance relaxation by an algebraic decay term. The analytical part

  5. Cytoskeletal actin dynamics shape a ramifying actin network underpinning immunological synapse formation

    DEFF Research Database (Denmark)

    Fritzsche, Marco; Fernandes, Ricardo A.; Chang, Veronica T.

    2017-01-01

    optical microscopes to analyze resting and activated T cells, we show that, following contact formation with activating surfaces, these cells sequentially rearrange their cortical actin across the entire cell, creating a previously unreported ramifying actin network above the immunological synapse...

  6. Advanced Modulation Formats in Cognitive Optical Networks: EU project CHRON Demonstration

    DEFF Research Database (Denmark)

    Borkowski, Robert; Caballero Jambrina, Antonio; Klonidis, Dimitris

    2014-01-01

    We demonstrate real-time path establishment and switching of coherent modulation formats (QPSK, 16QAM) within an optical network driven by cognitive algorithms. Cognition aims at autonomous configuration optimization to satisfy quality of transmission requirements.......We demonstrate real-time path establishment and switching of coherent modulation formats (QPSK, 16QAM) within an optical network driven by cognitive algorithms. Cognition aims at autonomous configuration optimization to satisfy quality of transmission requirements....

  7. Network formation determined by the diffusion process of random walkers

    International Nuclear Information System (INIS)

    Ikeda, Nobutoshi

    2008-01-01

    We studied the diffusion process of random walkers in networks formed by their traces. This model considers the rise and fall of links determined by the frequency of transports of random walkers. In order to examine the relation between the formed network and the diffusion process, a situation in which multiple random walkers start from the same vertex is investigated. The difference in diffusion rate of random walkers according to the difference in dimension of the initial lattice is very important for determining the time evolution of the networks. For example, complete subgraphs can be formed on a one-dimensional lattice while a graph with a power-law vertex degree distribution is formed on a two-dimensional lattice. We derived some formulae for predicting network changes for the 1D case, such as the time evolution of the size of nearly complete subgraphs and conditions for their collapse. The networks formed on the 2D lattice are characterized by the existence of clusters of highly connected vertices and their life time. As the life time of such clusters tends to be small, the exponent of the power-law distribution changes from γ ≅ 1-2 to γ ≅ 3

  8. Digital Identity Formation: Socially Being Real and Present on Digital Networks

    Science.gov (United States)

    Bozkurt, Aras; Tu, Chih-Hsiung

    2016-01-01

    Social networks have become popular communication and interaction environments recently. As digital environments, so as ecosystems, they have potential in terms of networked learning as they fulfill some roles such as mediating an environment for digital identity formation and providing social and emotional presence. Based on this phenomenon, the…

  9. Overexpression of Mitofusin 2 inhibited oxidized low-density lipoprotein induced vascular smooth muscle cell proliferation and reduced atherosclerotic lesion formation in rabbit

    International Nuclear Information System (INIS)

    Guo Yanhong; Chen Kuanghueih; Gao Wei; Li Qian; Chen Li; Wang Guisong; Tang Jian

    2007-01-01

    Our previous studies have implies that Mitofusin 2 (Mfn2), which was progressively reduced in arteries from ApoE -/- mice during the development of atherosclerosis, may take part in pathogenesis of atherosclerosis. In this study, we found that overexpression of Mfn2 inhibited oxidized low-density lipoprotein or serum induced vascular smooth muscle cell proliferation by down-regulation of Akt and ERK phosphorylation. Then we investigated the in vivo role of Mfn2 on the development of atherosclerosis in rabbits using adenovirus expressing Mitofusin 2 gene (AdMfn2). By morphometric analysis we found overexpression of Mfn2 inhibited atherosclerotic lesion formation and intima/media ratio by 66.7% and 74.6%, respectively, compared with control group. These results suggest that local Mfn2 treatment suppresses the development of atherosclerosis in vivo in part by attenuating the smooth muscle cell proliferation induced by lipid deposition and vascular injury

  10. Cohesive subgroup formation : enabling and constraining effects of social capital in strategic technology alliance networks

    NARCIS (Netherlands)

    Duysters, G.M.; Lemmens, C.E.A.V.

    2002-01-01

    In this paper we will examine the role of embeddedness and social capital in the process of cohesive subgroup formation in strategic technology alliance networks. More in particular, we will investigate the social mechanisms that enable and enforce cohesive subgroup formation. We will argue that the

  11. A simplified memory network model based on pattern formations

    Science.gov (United States)

    Xu, Kesheng; Zhang, Xiyun; Wang, Chaoqing; Liu, Zonghua

    2014-12-01

    Many experiments have evidenced the transition with different time scales from short-term memory (STM) to long-term memory (LTM) in mammalian brains, while its theoretical understanding is still under debate. To understand its underlying mechanism, it has recently been shown that it is possible to have a long-period rhythmic synchronous firing in a scale-free network, provided the existence of both the high-degree hubs and the loops formed by low-degree nodes. We here present a simplified memory network model to show that the self-sustained synchronous firing can be observed even without these two necessary conditions. This simplified network consists of two loops of coupled excitable neurons with different synaptic conductance and with one node being the sensory neuron to receive an external stimulus signal. This model can be further used to show how the diversity of firing patterns can be selectively formed by varying the signal frequency, duration of the stimulus and network topology, which corresponds to the patterns of STM and LTM with different time scales. A theoretical analysis is presented to explain the underlying mechanism of firing patterns.

  12. INFORMATION SYSTEM OF AIRPORT NETWORK DEVELOPMENT MONITORING FORMATION

    Directory of Open Access Journals (Sweden)

    Oleg Smirnov

    2015-07-01

    Full Text Available The article analyzes the approaches to the development of information system in public administration of this important branch of transport civil aviation. In particular, it is shown that the application of algorithmic elements allows to increase the objectivity and transparency when making decisions regarding the regulation of development of the airport network.

  13. Nanoscaffold's stiffness affects primary cortical cell network formation

    NARCIS (Netherlands)

    Xie, Sijia; Schurink, Bart; Wolbers, F.; Lüttge, Regina; Hassink, Gerrit Cornelis

    2014-01-01

    Networks of neurons cultured on-chip can provide insights into both normal and disease-state brain function. The ability to guide neuronal growth in specific, artificially designed patterns allows us to study how brain function follows form. Primary cortical cells cultured on nanograting scaffolds,

  14. Informal Learning and Identity Formation in Online Social Networks

    Science.gov (United States)

    Greenhow, Christine; Robelia, Beth

    2009-01-01

    All students today are increasingly expected to develop technological fluency, digital citizenship, and other twenty-first century competencies despite wide variability in the quality of learning opportunities schools provide. Social network sites (SNSs) available via the internet may provide promising contexts for learning to supplement…

  15. Romantic relationship formation, maintenance and changes in personal networks

    NARCIS (Netherlands)

    Rözer, J.J.; Mollenhorst, G.; Volker, B.

    2015-01-01

    According to the social withdrawal hypothesis, a personal network becomes smaller when a person starts dating, cohabitates and marries. This phenomenon is widely established in the literature. However, these studies were usually done with cross-sectional data. As a consequence, it is still unclear

  16. Optimal Formation of Multirobot Systems Based on a Recurrent Neural Network.

    Science.gov (United States)

    Wang, Yunpeng; Cheng, Long; Hou, Zeng-Guang; Yu, Junzhi; Tan, Min

    2016-02-01

    The optimal formation problem of multirobot systems is solved by a recurrent neural network in this paper. The desired formation is described by the shape theory. This theory can generate a set of feasible formations that share the same relative relation among robots. An optimal formation means that finding one formation from the feasible formation set, which has the minimum distance to the initial formation of the multirobot system. Then, the formation problem is transformed into an optimization problem. In addition, the orientation, scale, and admissible range of the formation can also be considered as the constraints in the optimization problem. Furthermore, if all robots are identical, their positions in the system are exchangeable. Then, each robot does not necessarily move to one specific position in the formation. In this case, the optimal formation problem becomes a combinational optimization problem, whose optimal solution is very hard to obtain. Inspired by the penalty method, this combinational optimization problem can be approximately transformed into a convex optimization problem. Due to the involvement of the Euclidean norm in the distance, the objective function of these optimization problems are nonsmooth. To solve these nonsmooth optimization problems efficiently, a recurrent neural network approach is employed, owing to its parallel computation ability. Finally, some simulations and experiments are given to validate the effectiveness and efficiency of the proposed optimal formation approach.

  17. Angiología y cirugía vascular en la formación del médico general básico Angiology and vascular surgery in the formation of the basic comprehensive doctor

    Directory of Open Access Journals (Sweden)

    Gladys Rojas Reyes

    2007-09-01

    Full Text Available Los estudios epidemiológicos sobre las afecciones vasculares periféricas han demostrado que ocupan un lugar significativo en la morbilidad y mortalidad de la población adulta. Por lo tanto se hace necesario que el Médico General Básico, con el dominio de los conocimientos pertinentes para su formación pueda realizar la profilaxis, el diagnóstico precoz y la conducta a seguir en la comunidad de toda esta gama de afecciones vasculares. Dentro de estas patologías se encuentra incluido el llamado Pie diabético, de alta morbilidad y mortalidad, el cual no figura en el actual plan de estudio de Medicina. Por lo que los autores en el presente trabajo pretendieron realizar una propuesta donde quede incluida dicha entidad, para una correcta dirección del proceso docente educativo en la formación de este nuevo modelo, a partir de la universalización de la carrera de medicina y la nueva concepción de formación de los recursos humanos en el escenario docente de excelencia: el Policlínico Universitario, jugando un papel activo el estudiante como constructor de su conocimiento.Epidemiological studies on peripheral vascular disorders have showed them to have a significant place in morbidity and mortality rate in adults. Therefore, it is necessary for the basic comprehensive doctor, with mastering of the pertinent knowledge for his formation, to be able to perform prophylaxis, early diagnosis and behaviour in the community of all the group of vascular disorders. These pathologies include the so called diabetic foot, with a high morbidity and mortality rate, which is not included in the current syllabus of Medicine. Therefore the authors of this paper made a proposal so that this entity will be included for a correct direction of the educational teaching process in the creation of this new model. From the universalization of the Medicine major and the new conception of formation of human resources in the teaching scenario of excellence: University

  18. Vascular risk factor burden correlates with cerebrovascular reactivity but not resting state coactivation in the default mode network.

    Science.gov (United States)

    Tchistiakova, Ekaterina; Crane, David E; Mikulis, David J; Anderson, Nicole D; Greenwood, Carol E; Black, Sandra E; MacIntosh, Bradley J

    2015-11-01

    White matter hyperintensities (WMH) are prevalent among older adults and are often associated with cognitive decline and increased risk of stroke and dementia. Vascular risk factors (VRFs) are linked to WMH, yet the impact of multiple VRFs on gray matter function is still unclear. The goal of this study was to test for associations between the number of VRFs and cerebrovascular reactivity (CVR) and resting state (RS) coactivation among individuals with WMH. Twenty-nine participants with suspected WMH were grouped based on the number of VRFs (subgroups: 0, 1, or ≥2). CVR and RS coactivation were measured with blood oxygenation level-dependent (BOLD) imaging on a 3T magnetic resonance imaging (MRI) system during hypercapnia and rest, respectively. Default-mode (DMN), sensory-motor, and medial-visual networks, generated using independent component analysis of RS-BOLD, were selected as networks of interest (NOIs). CVR-BOLD was analyzed using two methods: 1) a model-based approach using CO2 traces, and 2) a dual-regression (DR) approach using NOIs as spatial inputs. Average CVR and RS coactivations within NOIs were compared between VRF subgroups. A secondary analysis investigated the correlation between CVR and RS coactivation. VRF subgroup differences were detected using DR-based CVR in the DMN (F20,2  = 5.17, P = 0.015) but not the model-based CVR nor RS coactivation. DR-based CVR was correlated with RS coactivation in the DMN (r(2)  = 0.28, P = 0.006) but not the sensory-motor nor medial-visual NOIs. In individuals with WMH, CVR in the DMN was inversely associated with the number of VRFs and correlated with RS coactivation. © 2015 Wiley Periodicals, Inc.

  19. DWI and complex brain network analysis predicts vascular cognitive impairment in spontaneous hypertensive rats undergoing executive function tests

    Directory of Open Access Journals (Sweden)

    Xavier eLópez-Gil

    2014-07-01

    Full Text Available The identification of biomarkers of vascular cognitive impairment is urgent for its early diagnosis. The aim of this study was to detect and monitor changes in brain structure and connectivity, and to correlate them with the decline in executive function. We examined the feasibility of early diagnostic magnetic resonance imaging to predict cognitive impairment before onset in an animal model of chronic hypertension: Spontaneously Hypertensive Rats. Cognitive performance was tested in an operant conditioning paradigm that evaluated learning, memory and behavioral flexibility skills. Behavioral tests were coupled with longitudinal diffusion weighted imaging acquired with 126 diffusion gradient directions and 0.3 mm3 isometric resolution at 10, 14, 18, 22, 26 and 40 weeks after birth. Diffusion weighted imaging was analyzed in 2 different ways, by regional characterization of diffusion tensor imaging indices, and by assessing changes in structural brain network organization based on Q-Ball tractography. Already at the first evaluated times, diffusion tensor imaging scalar maps revealed significant differences in many regions, suggesting loss of integrity in white and grey matter of spontaneously hypertensive rats when compared to normotensive control rats. In addition, graph theory analysis of the structural brain network demonstrated a significant decrease of hierarchical modularity, global and local efficacy, with predictive value as shown by regional 3-fold cross validation study. Moreover, these decreases were significantly correlated with the behavioral performance deficits observed at subsequent time points, suggesting that the diffusion weighted imaging and connectivity studies can unravel neuroimaging alterations even overt signs of cognitive impairment become apparent.

  20. FORMATION OF THE ICT COMPETENCE OF MANAGERIAL AND PEDAGOGICAL STAFF IN A NETWORKING

    Directory of Open Access Journals (Sweden)

    O. A. Kozlov

    2016-01-01

    Full Text Available The questions related to the preparation of modern pedagogical and managerial staff to implement the capabilities of information and communication technologies in the professional activities in terms of networking. The authors found that the scientific-pedagogical conditions of formation of the ICT competencies of management and teaching staff as the coordinator of modernization of education are: to form approaches and principles of formation of the ICT competencies of management and teaching staff and the willingness of the professional community in the formation of the ICT competencies of management and teaching staff as the modernization of the coordinators education in networking Determined ways and means to achieve teaching and administrative staff of professional ICT competence under network interaction. Said factors that provide an optimal model to achieve the professional pedagogical ICT competence and managerial personnel under network interaction.

  1. Inter-organizational relationships: promoters and restrictive factors in the formation of cooperation network

    Directory of Open Access Journals (Sweden)

    Marcos Antonio Gaspar

    2014-04-01

    Full Text Available The present paper had as aim to identify factors of inter-organizational relationships which promotes and restricts the formation of companies’ cooperation network, from two levels of analysis (organizational and inter-organizational. To achieve this goal, it was developed a descriptive-qualitative study, with prospecting for primary and secondary data on a cooperation network. The universe was composed by 41 participating companies associated to the analyzed network. The sampling procedure was for researcher’s accessibility and convenience. As a result, it was identified that the network is guided by goals of cooperation among the participating companies, in addition to representing the sector and provide services in the interests of the associates. The main factors influencing the formation of the network were: business center, marketing and training; but only training has been achieved satisfactorily. The business center and marketing factors have not yet been fully developed, being both identified as restrictive factors.

  2. Understanding the process of social network evolution: Online-offline integrated analysis of social tie formation.

    Science.gov (United States)

    Kwak, Doyeon; Kim, Wonjoon

    2017-01-01

    It is important to consider the interweaving nature of online and offline social networks when we examine social network evolution. However, it is difficult to find any research that examines the process of social tie formation from an integrated perspective. In our study, we quantitatively measure offline interactions and examine the corresponding evolution of online social network in order to understand the significance of interrelationship between online and offline social factors in generating social ties. We analyze the radio signal strength indicator sensor data from a series of social events to understand offline interactions among the participants and measure the structural attributes of their existing online Facebook social networks. By monitoring the changes in their online social networks before and after offline interactions in a series of social events, we verify that the ability to develop an offline interaction into an online friendship is tied to the number of social connections that participants previously had, while the presence of shared mutual friends between a pair of participants disrupts potential new connections within the pre-designed offline social events. Thus, while our integrative approach enables us to confirm the theory of preferential attachment in the process of network formation, the common neighbor theory is not supported. Our dual-dimensional network analysis allows us to observe the actual process of social network evolution rather than to make predictions based on the assumption of self-organizing networks.

  3. Understanding the process of social network evolution: Online-offline integrated analysis of social tie formation.

    Directory of Open Access Journals (Sweden)

    Doyeon Kwak

    Full Text Available It is important to consider the interweaving nature of online and offline social networks when we examine social network evolution. However, it is difficult to find any research that examines the process of social tie formation from an integrated perspective. In our study, we quantitatively measure offline interactions and examine the corresponding evolution of online social network in order to understand the significance of interrelationship between online and offline social factors in generating social ties. We analyze the radio signal strength indicator sensor data from a series of social events to understand offline interactions among the participants and measure the structural attributes of their existing online Facebook social networks. By monitoring the changes in their online social networks before and after offline interactions in a series of social events, we verify that the ability to develop an offline interaction into an online friendship is tied to the number of social connections that participants previously had, while the presence of shared mutual friends between a pair of participants disrupts potential new connections within the pre-designed offline social events. Thus, while our integrative approach enables us to confirm the theory of preferential attachment in the process of network formation, the common neighbor theory is not supported. Our dual-dimensional network analysis allows us to observe the actual process of social network evolution rather than to make predictions based on the assumption of self-organizing networks.

  4. A network architecture for precision formation flying using the IEEE 802.11 MAC Protocol

    Science.gov (United States)

    Clare, Loren P.; Gao, Jay L.; Jennings, Esther H.; Okino, Clayton

    2005-01-01

    Precision Formation Flying missions involve the tracking and maintenance of spacecraft in a desired geometric formation. The strong coupling of spacecraft in formation flying control requires inter-spacecraft communication to exchange information. In this paper, we present a network architecture that supports PFF control, from the initial random deployment phase to the final formation. We show that a suitable MAC layer for the application protocol is IEEE's 802.11 MAC protocol. IEEE 802.11 MAC has two modes of operations: DCF and PCF. We show that DCF is suitable for the initial deployment phase while switching to PCF when the spacecraft are in formation improves jitter and throughput. We also consider the effect of routing on protocol performance and suggest when it is profitable to turn off route discovery to achieve better network performance.

  5. TLR accessory molecule RP105 (CD180 is involved in post-interventional vascular remodeling and soluble RP105 modulates neointima formation.

    Directory of Open Access Journals (Sweden)

    Jacco C Karper

    Full Text Available BACKGROUND: RP105 (CD180 is TLR4 homologue lacking the intracellular TLR4 signaling domain and acts a TLR accessory molecule and physiological inhibitor of TLR4-signaling. The role of RP105 in vascular remodeling, in particular post-interventional remodeling is unknown. METHODS AND RESULTS: TLR4 and RP105 are expressed on vascular smooth muscle cells (VSMC as well as in the media of murine femoral artery segments as detected by qPCR and immunohistochemistry. Furthermore, the response to the TLR4 ligand LPS was stronger in VSMC from RP105(-/- mice resulting in a higher proliferation rate. In RP105(-/- mice femoral artery cuff placement resulted in an increase in neointima formation as compared to WT mice (4982 ± 974 µm(2 vs.1947 ± 278 µm(2,p = 0.0014. Local LPS application augmented neointima formation in both groups, but in RP105(-/- mice this effect was more pronounced (10316±1243 µm(2 vs.4208 ± 555 µm(2,p = 0.0002, suggesting a functional role for RP105. For additional functional studies, the extracellular domain of murine RP105 was expressed with or without its adaptor protein MD1 and purified. SEC-MALSanalysis showed a functional 2∶2 homodimer formation of the RP105-MD1 complex. This protein complex was able to block the TLR4 response in whole blood ex-vivo. In vivo gene transfer of plasmid vectors encoding the extracellular part of RP105 and its adaptor protein MD1 were performed to initiate a stable endogenous soluble protein production. Expression of soluble RP105-MD1 resulted in a significant reduction in neointima formation in hypercholesterolemic mice (2500 ± 573 vs.6581 ± 1894 µm(2,p<0.05, whereas expression of the single factors RP105 or MD1 had no effect. CONCLUSION: RP105 is a potent inhibitor of post-interventional neointima formation.

  6. Spectro-microscopic study of the formation of supramolecular networks

    Science.gov (United States)

    Sadowski, Jerzy T.

    2015-03-01

    Metal-organic frameworks (MOFs) are emerging as a new class of materials for CO2 capture. There are many fundamental questions, including the optimum pore size and arrangement of the molecules in the structure to achieve highest CO2 uptake. As only the surface is of interest for potential applications such as heterogeneous catalysis, nano-templating, and sensing, 2D analogs of MOFs can serve as good model systems. Utilizing capabilities of LEEM/PEEM for non-destructive interrogation of the real-time molecular self-assembly, we investigated supramolecular systems based on carboxylic acid-metal complexes, such as trimesic and mellitic acid, doped with transition metals. Such 2D networks act as host systems for transition-metal phthalocyanines (MPc; M = Fe, Ti, Sc) and the electrostatic interactions of CO2 molecules with transition metal ions, can be tuned by controlling the type of TM ion and the size of the pore in the host network. The understanding of directed self-assembly by controlling the molecule-substrate interaction can enable us to engineer the pore size and density, and thus tune the host's chemical activity. Research carried out at the Center for Functional Nanomaterials and National Synchrotron Light Source, Brookhaven National Laboratory, which are supported by the U.S. Department of Energy, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10.

  7. Secure Group Formation Protocol for a Medical Sensor Network Prototype

    DEFF Research Database (Denmark)

    Andersen, Jacob

    2009-01-01

    , and experience from user workshops and observations of clinicians at work on a hospital ward show that if the security mechanisms are not well designed, the technology is either rejected altogether, or they are circumvented leaving the system wide open to attacks. Our work targets the problem of designing......Designing security mechanisms such as privacy and access control for medical sensor networks is a challenging task; as such systems may be operated very frequently, at a quick pace, and at times in emergency situations. Understandably, clinicians hold extra unproductive tasks in low regard...... wireless sensors to be both secure and usable by exploring different solutions on a fully functional prototype platform. In this paper, we present an Elliptic Curve Cryptography (ECC) based protocol, which offers fully secure sensor set-up in a few seconds on standard (Telos) hardware. We evaluate...

  8. Nuclear traffic and peloton formation in fungal networks

    Science.gov (United States)

    Roper, Marcus; Hickey, Patrick; Lewkiewicz, Stephanie; Dressaire, Emilie; Read, Nick

    2013-11-01

    Hyphae, the network of microfluidic pipes that make up a growing fungal cell, must balance their function as conduits for the transport of nuclei with other cellular functions including secretion and growth. Constant flow of nuclei may interfere with the protein traffic that enables other functions to be performed. Live-cell imaging reveals that nuclear flows are anti-congestive; that groups of nuclei flow faster than single nuclei, and that nuclei sweep through the colony in dense clumps. We call these clumps pelotons, after the term used to describe groups of cycle racers slip-streaming off each other. Because of the pelotons, individual hyphae transport nuclei only intermittently, producing long intervals in which hyphae can perform their other functions. Modeling reveals how pelotons are created by interactions between nuclei and the hyphal cytoskeleton, and reveal the control that the fungus enjoys over peloton assembly and timing.

  9. Opinion formation driven by PageRank node influence on directed networks

    Science.gov (United States)

    Eom, Young-Ho; Shepelyansky, Dima L.

    2015-10-01

    We study a two states opinion formation model driven by PageRank node influence and report an extensive numerical study on how PageRank affects collective opinion formations in large-scale empirical directed networks. In our model the opinion of a node can be updated by the sum of its neighbor nodes' opinions weighted by the node influence of the neighbor nodes at each step. We consider PageRank probability and its sublinear power as node influence measures and investigate evolution of opinion under various conditions. First, we observe that all networks reach steady state opinion after a certain relaxation time. This time scale is decreasing with the heterogeneity of node influence in the networks. Second, we find that our model shows consensus and non-consensus behavior in steady state depending on types of networks: Web graph, citation network of physics articles, and LiveJournal social network show non-consensus behavior while Wikipedia article network shows consensus behavior. Third, we find that a more heterogeneous influence distribution leads to a more uniform opinion state in the cases of Web graph, Wikipedia, and Livejournal. However, the opposite behavior is observed in the citation network. Finally we identify that a small number of influential nodes can impose their own opinion on significant fraction of other nodes in all considered networks. Our study shows that the effects of heterogeneity of node influence on opinion formation can be significant and suggests further investigations on the interplay between node influence and collective opinion in networks.

  10. Time and flow-dependent changes in the p27(kip1) gene network drive maladaptive vascular remodeling.

    Science.gov (United States)

    DeSart, Kenneth M; Butler, Khayree; O'Malley, Kerri A; Jiang, Zhihua; Berceli, Scott A

    2015-11-01

    Although clinical studies have identified that a single nucleotide polymorphism in the p27(kip1) gene is associated with success or failure after vein bypass grafting, the underlying mechanisms for this difference are not well defined. Using a high-throughput approach in a flow-dependent vein graft model, we explored the differences in p27(kip1)-related genes that drive the enhanced hyperplastic response under low-flow conditions. Bilateral rabbit carotid artery interposition grafts with jugular vein were placed with a unilateral distal outflow branch ligation to create differential flow states. Grafts were harvested at 2 hours and at 1, 3, 7, 14, and 28 days after implantation, measured for neointimal area, and assayed for cell proliferation. Whole-vessel messenger RNA was isolated and analyzed using an Affymetrix (Santa Clara, Calif) gene array platform. Ingenuity Pathway Analysis (Ingenuity, Redwood City, Calif) was used to identify the gene networks surrounding p27(kip1). This gene set was then analyzed for temporal expression changes after graft placement and for differential expression in the alternate flow conditions. Outflow branch ligation resulted in an eightfold difference in mean flow rates throughout the 28-day perfusion period (P Flow reduction led to a robust hyperplastic response, resulting in a significant increase in intimal area by 7 days (0.13 ± 0.04 mm(2) vs 0.014 ± 0.006 mm(2); P flow grafts demonstrated a burst of actively dividing intimal cells (36.4 ± 9.4 cells/mm(2) vs 11.5 ± 1.9 cells/mm(2); P = .04). Sixty-five unique genes within the microarray were identified as components of the p27(kip1) network. At a false discovery rate of 0.05, 26 genes demonstrated significant temporal changes, and two dominant patterns of expression were identified. Class comparison analysis identified differential expression of 11 genes at 2 hours and seven genes and 14 days between the high-flow and low-flow grafts (P flow and shear stress result in

  11. Low-Dimensional Network Formation in Molten Sodium Carbonate.

    Science.gov (United States)

    Wilding, Martin C; Wilson, Mark; Alderman, Oliver L G; Benmore, Chris; Weber, J K R; Parise, John B; Tamalonis, Anthony; Skinner, Lawrie

    2016-04-15

    Molten carbonates are highly inviscid liquids characterized by low melting points and high solubility of rare earth elements and volatile molecules. An understanding of the structure and related properties of these intriguing liquids has been limited to date. We report the results of a study of molten sodium carbonate (Na2CO3) which combines high energy X-ray diffraction, containerless techniques and computer simulation to provide insight into the liquid structure. Total structure factors (F(x)(Q)) are collected on the laser-heated carbonate spheres suspended in flowing gases of varying composition in an aerodynamic levitation furnace. The respective partial structure factor contributions to F(x)(Q) are obtained by performing molecular dynamics simulations treating the carbonate anions as flexible entities. The carbonate liquid structure is found to be heavily temperature-dependent. At low temperatures a low-dimensional carbonate chain network forms, at T = 1100 K for example ~55% of the C atoms form part of a chain. The mean chain lengths decrease as temperature is increased and as the chains become shorter the rotation of the carbonate anions becomes more rapid enhancing the diffusion of Na(+) ions.

  12. Motif formation and industry specific topologies in the Japanese business firm network

    Science.gov (United States)

    Maluck, Julian; Donner, Reik V.; Takayasu, Hideki; Takayasu, Misako

    2017-05-01

    Motifs and roles are basic quantities for the characterization of interactions among 3-node subsets in complex networks. In this work, we investigate how the distribution of 3-node motifs can be influenced by modifying the rules of an evolving network model while keeping the statistics of simpler network characteristics, such as the link density and the degree distribution, invariant. We exemplify this problem for the special case of the Japanese Business Firm Network, where a well-studied and relatively simple yet realistic evolving network model is available, and compare the resulting motif distribution in the real-world and simulated networks. To better approximate the motif distribution of the real-world network in the model, we introduce both subgraph dependent and global additional rules. We find that a specific rule that allows only for the merging process between nodes with similar link directionality patterns reduces the observed excess of densely connected motifs with bidirectional links. Our study improves the mechanistic understanding of motif formation in evolving network models to better describe the characteristic features of real-world networks with a scale-free topology.

  13. System level mechanisms of adaptation, learning, memory formation and evolvability: the role of chaperone and other networks.

    Science.gov (United States)

    Gyurko, David M; Soti, Csaba; Stetak, Attila; Csermely, Peter

    2014-05-01

    During the last decade, network approaches became a powerful tool to describe protein structure and dynamics. Here, we describe first the protein structure networks of molecular chaperones, then characterize chaperone containing sub-networks of interactomes called as chaperone-networks or chaperomes. We review the role of molecular chaperones in short-term adaptation of cellular networks in response to stress, and in long-term adaptation discussing their putative functions in the regulation of evolvability. We provide a general overview of possible network mechanisms of adaptation, learning and memory formation. We propose that changes of network rigidity play a key role in learning and memory formation processes. Flexible network topology provides ' learning-competent' state. Here, networks may have much less modular boundaries than locally rigid, highly modular networks, where the learnt information has already been consolidated in a memory formation process. Since modular boundaries are efficient filters of information, in the 'learning-competent' state information filtering may be much smaller, than after memory formation. This mechanism restricts high information transfer to the 'learning competent' state. After memory formation, modular boundary-induced segregation and information filtering protect the stored information. The flexible networks of young organisms are generally in a 'learning competent' state. On the contrary, locally rigid networks of old organisms have lost their 'learning competent' state, but store and protect their learnt information efficiently. We anticipate that the above mechanism may operate at the level of both protein-protein interaction and neuronal networks.

  14. Formation Features of the Customer Segments for the Network Organizations in the Smart Era

    Directory of Open Access Journals (Sweden)

    Elena V. Yaroshenko

    2017-01-01

    Full Text Available Modern network society is based on the advances of information era of Smart, connecting information and communication technologies, intellectual resources and new forms of managing in the global electronic space. It leads to domination of network forms of the organization of economic activity. Many experts prove the importance of segmentation process of consumers when developing competitive strategy of the organization. Every company needs a competent segmentation of the customer base, allowing to concentrate the attention on satisfaction of requirements of the most perspective client segments. The network organizations have specific characteristics; therefore, it is important to understand how they can influence on the formation of client profiles. It causes the necessity of the network organizations’ research in terms of management of high-profitable client segments.The aim of this study is to determine the characteristics of the market segmentation and to choose the key customers for the network organizations. This purpose has defined the statement and the solution of the following tasks: to explore characteristic features of the network forms of the organization of economic activity of the companies, their prospects, Smart technologies’ influence on them; to reveal the work importance with different client profiles; to explore the existing methods and tools of formation of key customer segments; to define criteria for selection of key groups; to reveal the characteristics of customer segments’ formation for the network organizations.In the research process, methods of the system analysis, a method of analogies, methods of generalizations, a method of the expert evaluations, methods of classification and clustering were applied.This paper explores the characteristics and principles of functioning of network organizations, the appearance of which is directly linked with the development of Smart society. It shows the influence on the

  15. Network centrality based team formation: A case study on T-20 cricket

    Directory of Open Access Journals (Sweden)

    Paramita Dey

    2017-07-01

    Full Text Available This paper proposes and evaluates the novel utilization of small world network properties for the formation of team of players with both best performances and best belongingness within the team network. To verify this concept, this methodology is applied to T-20 cricket teams. The players are treated as nodes of the network, whereas the number of interactions between team members is denoted as the edges between those nodes. All intra country networks form the cricket network for this case study. Analysis of the networks depicts that T-20 cricket network inherits all characteristics of small world network. Making a quantitative measure for an individual performance in the team sports is important with respect to the fact that for team selection of an International match, from pool of best players, only eleven players can be selected for the team. The statistical record of each player considered as a traditional way of quantifying the performance of a player. But the other criteria such as performing against a strong opponent or performance as an effective team member such as fielding, running between the wickets, good partnership deserves more credential. In this paper a revised method based on social networking is presented to quantify the quality of team belongingness and efficiency of each player. The application of Social Network Analysis (SNA is explored to measure performances and the rank of the players. A bidirectional weighted network of players is generated using the information collected from T-20 cricket (2014–2016 and used for network analysis. Thus team was formed based on that ranking and compared with their IPL (Indian Premier League performances of 2016.

  16. Intraperitoneal pressure: ascitic fluid and splanchnic vascular pressures, and their role in prevention and formation of ascites

    DEFF Research Database (Denmark)

    Henriksen, Jens Henrik Sahl; Stage, J G; Schlichting, P

    1980-01-01

    Seventeen patients with ascites due to cirrhosis underwent hepatic venous catheterization and pressure measurement in the ascitic fluid. Intraperitoneal fluid hydrostatic pressure (IFP) ranged 3.5-22, mean 11.2 mm Hg, and correlated closely to the pressure in the inferior vena cava (r = 0.97, P ... that ascitic fluid stems the pressures in the splanchnic venous vascular bed up to a higher level, but that the transmural hydrostatic pressure difference decreases simultaneously. The results are discussed in relation to the local 'oedema-preventing' mechanisms: (a) increased interstitial hydrostatic fluid.......001), which was on average 1.8 mmHg above that of ascitic fluid (P pressure (WHVP) (range 19-43, mean 32 mmHg) correlated directly to IFP (0.89, P

  17. Mechanisms of lumen formation during sprouting angiogenesis in vivo

    OpenAIRE

    Gebala, V. M.

    2016-01-01

    During development, vascular networks expand following a process known as sprouting angiogenesis. New vascular branches arise from pre-existing vessels through the coordinated migration and proliferation of endothelial cells, and eventually connect to form new vascular loops. The functionality of these new vessel segments is dependent on the opening of a central lumen to allow perfusion. While mechanisms of lumen formation during the establishment of the primary vasculature by vasculogenesis ...

  18. Glass formation via structural fragmentation of a 2D coordination network.

    Science.gov (United States)

    Umeyama, D; Funnell, N P; Cliffe, M J; Hill, J A; Goodwin, A L; Hijikata, Y; Itakura, T; Okubo, T; Horike, S; Kitagawa, S

    2015-08-18

    The structure of a glass obtained by the melt quenching of a two-dimensional (2D) coordination network was examined. X-ray analyses disclosed a 2D-to-0D structural transformation before and after glass formation. The mechanism is unique to coordination compounds, as it is characterized by labile and flexible coordination bonds.

  19. The effect of oil type on network formation by protein aggregates into oleogels

    NARCIS (Netherlands)

    Vries, de Auke; Lopez Gomez, Yuly; Linden, van der Erik; Scholten, Elke

    2017-01-01

    The aim of this study was to assess the effect of oil type on the network formation of heat-set protein aggregates in liquid oil. The gelling properties of such aggregates to structure oil into so-called ‘oleogels’ are related to both the particle-particle and particle-solvent interactions. To

  20. Project team formation support for self-directed learners in social learning networks

    NARCIS (Netherlands)

    Spoelstra, Howard; Van Rosmalen, Peter; Sloep, Peter

    2012-01-01

    Spoelstra, H., Van Rosmalen, P., & Sloep, P. B. (2012). Project team formation support for self-directed learners in social learning networks. In P. Kommers, P. Isaias, & N. Bessis (Eds.), Proceedings of the IADIS International Conference on Web Based Communities and Social Media (ICWBC & SM 2012)

  1. Neural Network Observer-Based Finite-Time Formation Control of Mobile Robots

    Directory of Open Access Journals (Sweden)

    Caihong Zhang

    2014-01-01

    Full Text Available This paper addresses the leader-following formation problem of nonholonomic mobile robots. In the formation, only the pose (i.e., the position and direction angle of the leader robot can be obtained by the follower. First, the leader-following formation is transformed into special trajectory tracking. And then, a neural network (NN finite-time observer of the follower robot is designed to estimate the dynamics of the leader robot. Finally, finite-time formation control laws are developed for the follower robot to track the leader robot in the desired separation and bearing in finite time. The effectiveness of the proposed NN finite-time observer and the formation control laws are illustrated by both qualitative analysis and simulation results.

  2. Formation of Molecular Networks: Tailored Quantum Boxes and Behavior of Adsorbed CO in Them

    Science.gov (United States)

    Wyrick, Jon; Sun, Dezheng; Kim, Dae-Ho; Cheng, Zhihai; Lu, Wenhao; Zhu, Yeming; Luo, Miaomiao; Kim, Yong Su; Rotenberg, Eli; Kim, Kwangmoo; Einstein, T. L.; Bartels, Ludwig

    2011-03-01

    We show that the behavior of CO adsorbed into the pores of large regular networks on Cu(111) is significantly affected by their nano-scale lateral confinement and that formation of the networks themselves is directed by the Shockley surface state. Saturation coverages of CO are found to exhibit persistent dislocation lines; at lower coverages their mobility increases. Individual CO within the pores titrate the surface state, providing crucial information for understanding formation of the network as a result of optimization of the number N of electrons bound within each pore. Determination of N is based on quinone-coverage-dependent UPS data and an analysis of states of particles in a pore-shaped box (verified by CO's titration); a wide range of possible pore shapes and sizes has been considered. Work at UCR supported by NSF CHE 07-49949; at UMD by NSF CHE 07-50334 & UMD NSF-MRSEC DMR 05-20471.

  3. Opinion formation and distribution in a bounded-confidence model on various networks

    Science.gov (United States)

    Meng, X. Flora; Van Gorder, Robert A.; Porter, Mason A.

    2018-02-01

    In the social, behavioral, and economic sciences, it is important to predict which individual opinions eventually dominate in a large population, whether there will be a consensus, and how long it takes for a consensus to form. Such ideas have been studied heavily both in physics and in other disciplines, and the answers depend strongly both on how one models opinions and on the network structure on which opinions evolve. One model that was created to study consensus formation quantitatively is the Deffuant model, in which the opinion distribution of a population evolves via sequential random pairwise encounters. To consider heterogeneity of interactions in a population along with social influence, we study the Deffuant model on various network structures (deterministic synthetic networks, random synthetic networks, and social networks constructed from Facebook data). We numerically simulate the Deffuant model and conduct regression analyses to investigate the dependence of the time to reach steady states on various model parameters, including a confidence bound for opinion updates, the number of participating entities, and their willingness to compromise. We find that network structure and parameter values both have important effects on the convergence time and the number of steady-state opinion groups. For some network architectures, we observe that the relationship between the convergence time and model parameters undergoes a transition at a critical value of the confidence bound. For some networks, the steady-state opinion distribution also changes from consensus to multiple opinion groups at this critical value.

  4. Formation of nanoscale networks: selectively swelling amphiphilic block copolymers with CO2-expanded liquids.

    Science.gov (United States)

    Gong, Jianliang; Zhang, Aijuan; Bai, Hua; Zhang, Qingkun; Du, Can; Li, Lei; Hong, Yanzhen; Li, Jun

    2013-02-07

    Polymeric films with nanoscale networks were prepared by selectively swelling an amphiphilic diblock copolymer, polystyrene-block-poly(4-vinylpyridine) (PS-b-P4VP), with the CO(2)-expanded liquid (CXL), CO(2)-methanol. The phase behavior of the CO(2)-methanol system was investigated by both theoretical calculation and experiments, revealing that methanol can be expanded by CO(2), forming homogeneous CXL under the experimental conditions. When treated with the CO(2)-methanol system, the spin cast compact PS-b-P4VP film was transformed into a network with interconnected pores, in a pressure range of 12-20 MPa and a temperature range of 45-60 °C. The formation mechanism of the network, involving plasticization of PS and selective swelling of P4VP, was proposed. Because the diblock copolymer diffusion process is controlled by the activated hopping of individual block copolymer chains with the thermodynamic barrier for moving PVP segments from one to another, the formation of the network structures is achieved in a short time scale and shows "thermodynamically restricted" character. Furthermore, the resulting polymer networks were employed as templates, for the preparation of polypyrrole networks, by an electrochemical polymerization process. The prepared porous polypyrrole film was used to fabricate a chemoresistor-type gas sensor which showed high sensitivity towards ammonia.

  5. Network formation, governance, and evolution in public health: the North American Quitline Consortium case.

    Science.gov (United States)

    Provan, Keith G; Beagles, Jonathan E; Leischow, Scott J

    2011-01-01

    Collaborative networks of health organizations have received a great deal of attention in recent years as a way of enhancing the flow of information and coordination of services. However, relatively little is known about how such networks are formed and evolve, especially outside a local, community-based setting. This article is an in-depth discussion of the evolution of the North American Quitline Consortium (NAQC). The NAQC is a network of U.S. and Canadian organizations that provide telephone-based counseling and related services to people trying to quit smoking. The research draws on data from interviews, documents, and a survey of NAQC members to assess how the network emerged, became formalized, and effectively governed. The findings provide an understanding of how multiregional public health networks evolve, while building on and extending the broader literature on organizational networks in other sectors and settings. Specifically, we found that the network form that ultimately emerged was a product of the back-and-forth interplay between the internal needs and goals of those organizations that would ultimately become network members, in this case, state-, and provincial-level tobacco quitline organizations. We also found that network formation, and then governance through a network administrative organization, was driven by important events and shifts in the external environment, including the impact and influence of major national organizations. The results of the study provide health care leaders and policy officials an understanding of how the activities of a large number of organizations having a common health goal, but spanning multiple states and countries, might be coordinated and integrated through the establishment of a formal network.

  6. Hydro-mechanical foundation for blood swirling vortex flows formation in the cardio-vascular system and the problem of artificial heart creation

    Directory of Open Access Journals (Sweden)

    Sergey G. Chefranov

    2013-11-01

    Full Text Available Leonardo da Vinci perhaps was the first who paid attention to the energetic efficiency of existence of vortices emerging near sines of Valsalva and defining normal functioning (opening of aortal valve. However up to now a fundamental problem of defining of mechanisms of mysterious energetic efficiency of functioning of cardio-vascular system (CVS of blood feeding of the organism is still remaining significantly not solved and this is, for example, one of the main restriction for the creation of artificial heart and corresponding valve systems. In the present paper, results witnessing possible important role of the very hydro-mechanical mechanism in the realization of the noted energetic efficiency of CVS due to formation in the CVS of spiral structural organization of the arterial blood flow observed by methods of MRT and color Doppler-measuring in the left ventricular of the heart and in aorta.

  7. Effect of hydro mechanical coupling on natural fracture network formation in sedimentary basins

    Science.gov (United States)

    Ouraga, Zady; Guy, Nicolas; Pouya, Amade

    2018-05-01

    In sedimentary basin context, numerous phenomena, depending on the geological time span, can result in natural fracture network formation. In this paper, fracture network and dynamic fracture spacing triggered by significant sedimentation rate are studied considering mode I fracture propagation using a coupled hydro-mechanical numerical methods. The focus is put on synthetic geological structure under a constant sedimentation rate on its top. This model contains vertical fracture network initially closed and homogeneously distributed. The fractures are modelled with cohesive zone model undergoing damage and the flow is described by Poiseuille's law. The effect of the behaviour of the rock is studied and the analysis leads to a pattern of fracture network and fracture spacing in the geological layer.

  8. Optimizing combination of vascular endothelial growth factor and mesenchymal stem cells on ectopic bone formation in SCID mice

    DEFF Research Database (Denmark)

    Dreyer, Chris H; Kjaergaard, Kristian; Ditzel, Nicholas

    2017-01-01

    combined immunodeficient (SCID) mice were used in this study to evaluate optimal time points for VEGF stimulation to increase bone formation. METHODS: Twenty-eight SCID (NOD.CB17-Prkdcscid/J) mice had hydroxyapatite granules seeded with 5 × 105MSCs inserted subcutaneous. Pellets released VEGF on days 1...

  9. Master stability functions reveal diffusion-driven pattern formation in networks

    Science.gov (United States)

    Brechtel, Andreas; Gramlich, Philipp; Ritterskamp, Daniel; Drossel, Barbara; Gross, Thilo

    2018-03-01

    We study diffusion-driven pattern formation in networks of networks, a class of multilayer systems, where different layers have the same topology, but different internal dynamics. Agents are assumed to disperse within a layer by undergoing random walks, while they can be created or destroyed by reactions between or within a layer. We show that the stability of homogeneous steady states can be analyzed with a master stability function approach that reveals a deep analogy between pattern formation in networks and pattern formation in continuous space. For illustration, we consider a generalized model of ecological meta-food webs. This fairly complex model describes the dispersal of many different species across a region consisting of a network of individual habitats while subject to realistic, nonlinear predator-prey interactions. In this example, the method reveals the intricate dependence of the dynamics on the spatial structure. The ability of the proposed approach to deal with this fairly complex system highlights it as a promising tool for ecology and other applications.

  10. Digital-Networked Images as Personal Acts of Political Expression: New Categories for Meaning Formation

    Directory of Open Access Journals (Sweden)

    Mona Kasra

    2017-12-01

    Full Text Available This article examines the growing use of digital-networked images, specifically online self-portraits or “selfies”, as deliberate and personal acts of political expression and the ways in which meaning evolves and expands from their presence on the Internet. To understand the role of digital-networked images as a site for engaging in a personal and connective “visual” action that leads to formation of transient communities, the author analyzes the nude self-portrait of the young Egyptian woman Aliaa Magda Elmahdy, which during the Egyptian uprisings in 2011 drew attention across social media. As an object of analysis this image is a prime example of the use of digital-networked images in temporally intentional distribution, and as an instance of political enactment unique to this era. This article also explains the concept of participatory narratives as an ongoing process of meaning formation in the digital-networked image, shaped by the fluidity of the multiple and immediate textual narratives, visual derivatives, re-appropriation, and remixes contributed by other interested viewers. The online circulation of digital-networked images in fact culminates in a flow of ever-changing and overarching narratives, broadening the contextual scope around which images are traditionally viewed.

  11. The role of endogenous and exogenous mechanisms in the formation of R&D networks

    Science.gov (United States)

    Tomasello, Mario V.; Perra, Nicola; Tessone, Claudio J.; Karsai, Márton; Schweitzer, Frank

    2014-01-01

    We develop an agent-based model of strategic link formation in Research and Development (R&D) networks. Empirical evidence has shown that the growth of these networks is driven by mechanisms which are both endogenous to the system (that is, depending on existing alliances patterns) and exogenous (that is, driven by an exploratory search for newcomer firms). Extant research to date has not investigated both mechanisms simultaneously in a comparative manner. To overcome this limitation, we develop a general modeling framework to shed light on the relative importance of these two mechanisms. We test our model against a comprehensive dataset, listing cross-country and cross-sectoral R&D alliances from 1984 to 2009. Our results show that by fitting only three macroscopic properties of the network topology, this framework is able to reproduce a number of micro-level measures, including the distributions of degree, local clustering, path length and component size, and the emergence of network clusters. Furthermore, by estimating the link probabilities towards newcomers and established firms from the data, we find that endogenous mechanisms are predominant over the exogenous ones in the network formation, thus quantifying the importance of existing structures in selecting partner firms. PMID:25022561

  12. The role of endogenous and exogenous mechanisms in the formation of R&D networks

    Science.gov (United States)

    Tomasello, Mario V.; Perra, Nicola; Tessone, Claudio J.; Karsai, Márton; Schweitzer, Frank

    2014-07-01

    We develop an agent-based model of strategic link formation in Research and Development (R&D) networks. Empirical evidence has shown that the growth of these networks is driven by mechanisms which are both endogenous to the system (that is, depending on existing alliances patterns) and exogenous (that is, driven by an exploratory search for newcomer firms). Extant research to date has not investigated both mechanisms simultaneously in a comparative manner. To overcome this limitation, we develop a general modeling framework to shed light on the relative importance of these two mechanisms. We test our model against a comprehensive dataset, listing cross-country and cross-sectoral R&D alliances from 1984 to 2009. Our results show that by fitting only three macroscopic properties of the network topology, this framework is able to reproduce a number of micro-level measures, including the distributions of degree, local clustering, path length and component size, and the emergence of network clusters. Furthermore, by estimating the link probabilities towards newcomers and established firms from the data, we find that endogenous mechanisms are predominant over the exogenous ones in the network formation, thus quantifying the importance of existing structures in selecting partner firms.

  13. Formation of lamellar cross bridges in the annulus fibrosus of the intervertebral disc is a consequence of vascular regression.

    Science.gov (United States)

    Smith, Lachlan J; Elliott, Dawn M

    2011-05-01

    Cross bridges are radial structures within the highly organized lamellar structure of the annulus fibrosus of the intervertebral disc that connect two or more non-consecutive lamellae. Their origin and function are unknown. During fetal development, blood vessels penetrate deep within the AF and recede during postnatal growth. We hypothesized that cross bridges are the pathways left by these receding blood vessels. Initially, the presence of cross bridges was confirmed in cadaveric human discs aged 25 and 53 years. Next, L1-L2 intervertebral discs (n=4) from sheep ranging in age from 75 days fetal gestation to adult were processed for paraffin histology. Mid-sagittal sections were immunostained for endothelial cell marker PECAM-1. The anterior and posterior AF were imaged using differential interference contrast microscopy, and the following parameters were quantified: total number of distinct lamellae, total number of cross bridges, percentage of cross bridges staining positive for PECAM-1, cross bridge penetration depth (% total lamellae), and PECAM-1 positive cross bridge penetration depth. Cross bridges were first observed at 100 days fetal gestation. The overall number peaked in neonates then remained relatively unchanged. The percentage of PECAM-1 positive cross bridges declined progressively from almost 100% at 100 days gestation to less than 10% in adults. Cross bridge penetration depth peaked in neonates then remained unchanged at subsequent ages. Depth of PECAM-1 positive cross bridges decreased progressively after birth. Findings were similar for both the anterior and posterior. The AF lamellar architecture is established early in development. It later becomes disrupted as a consequence of vascularization. Blood vessels then recede, perhaps due to increasing mechanical stresses in the surrounding matrix. In this study we present evidence that the pathways left by receding blood vessels remain as lamellar cross bridges. It is unclear whether the presence

  14. Opinion formation in a social network: The role of human activity

    Science.gov (United States)

    Grabowski, Andrzej

    2009-03-01

    The model of opinion formation in human population based on social impact theory is investigated numerically. On the basis of a database received from the on-line game server, we examine the structure of social network and human dynamics. We calculate the activity of individuals, i.e. the relative time devoted daily to interactions with others in the artificial society. We study the influence of correlation between the activity of an individual and its connectivity on the process of opinion formation. We find that such correlations have a significant influence on the temperature of the phase transition and the effect of the mass media, modeled as an external stimulation acting on the social network.

  15. Platelet lysate gel and endothelial progenitors stimulate microvascular network formation in vitro: tissue engineering implications.

    Science.gov (United States)

    Fortunato, Tiago M; Beltrami, Cristina; Emanueli, Costanza; De Bank, Paul A; Pula, Giordano

    2016-05-04

    Revascularisation is a key step for tissue regeneration and complete organ engineering. We describe the generation of human platelet lysate gel (hPLG), an extracellular matrix preparation from human platelets able to support the proliferation of endothelial colony forming cells (ECFCs) in 2D cultures and the formation of a complete microvascular network in vitro in 3D cultures. Existing extracellular matrix preparations require addition of high concentrations of recombinant growth factors and allow only limited formation of capillary-like structures. Additional advantages of our approach over existing extracellular matrices are the absence of any animal product in the composition hPLG and the possibility of obtaining hPLG from patients to generate homologous scaffolds for re-implantation. This discovery has the potential to accelerate the development of regenerative medicine applications based on implantation of microvascular networks expanded ex vivo or the generation of fully vascularised organs.

  16. The formation of synchronization cliques during the development of modular neural networks

    International Nuclear Information System (INIS)

    Fuchs, Einat; Ayali, Amir; Ben-Jacob, Eshel; Boccaletti, Stefano

    2009-01-01

    Modular organization is a special feature shared by many biological and social networks alike. It is a hallmark for systems exhibiting multitasking, in which individual tasks are performed by separated and yet coordinated functional groups. Understanding how networks of segregated modules develop to support coordinated multitasking functionalities is the main topic of the current study. Using simulations of biologically inspired neuronal networks during development, we study the formation of functional groups (cliques) and inter-neuronal synchronization. The results indicate that synchronization cliques first develop locally according to the explicit network topological organization. Later on, at intermediate connectivity levels, when networks have both local segregation and long-range integration, new synchronization cliques with distinctive properties are formed. In particular, by defining a new measure of synchronization centrality, we identify at these developmental stages dominant neurons whose functional centrality largely exceeds the topological one. These are generated mainly in a few dominant clusters that become the centers of the newly formed synchronization cliques. We show that by the local synchronization properties at the very early developmental stages, it is possible to predict with high accuracy which clusters will become dominant in later stages of network development

  17. Drug use Discrimination Predicts Formation of High-Risk Social Networks: Examining Social Pathways of Discrimination.

    Science.gov (United States)

    Crawford, Natalie D; Ford, Chandra; Rudolph, Abby; Kim, BoRin; Lewis, Crystal M

    2017-09-01

    Experiences of discrimination, or social marginalization and ostracism, may lead to the formation of social networks characterized by inequality. For example, those who experience discrimination may be more likely to develop drug use and sexual partnerships with others who are at increased risk for HIV compared to those without experiences of discrimination. This is critical as engaging in risk behaviors with others who are more likely to be HIV positive can increase one's risk of HIV. We used log-binomial regression models to examine the relationship between drug use, racial and incarceration discrimination with changes in the composition of one's risk network among 502 persons who use drugs. We examined both absolute and proportional changes with respect to sex partners, drug use partners, and injecting partners, after accounting for individual risk behaviors. At baseline, participants were predominately male (70%), black or Latino (91%), un-married (85%), and used crack (64%). Among those followed-up (67%), having experienced discrimination due to drug use was significantly related to increases in the absolute number of sex networks and drug networks over time. No types of discrimination were related to changes in the proportion of high-risk network members. Discrimination may increase one's risk of HIV acquisition by leading them to preferentially form risk relationships with higher-risk individuals, thereby perpetuating racial and ethnic inequities in HIV. Future social network studies and behavioral interventions should consider whether social discrimination plays a role in HIV transmission.

  18. In situ recording of particle network formation in liquids by ion conductivity measurements.

    Science.gov (United States)

    Pfaffenhuber, Christian; Sörgel, Seniz; Weichert, Katja; Bele, Marjan; Mundinger, Tabea; Göbel, Marcus; Maier, Joachim

    2011-09-21

    The formation of fractal silica networks from a colloidal initial state was followed in situ by ion conductivity measurements. The underlying effect is a high interfacial lithium ion conductivity arising when silica particles are brought into contact with Li salt-containing liquid electrolytes. The experimental results were modeled using Monte Carlo simulations and tested using confocal fluorescence laser microscopy and ζ-potential measurements.

  19. Formation of Neural Networks in 3D Scaffolds Fabricated by Means of Laser Microstereolithography.

    Science.gov (United States)

    Vedunova, M V; Timashev, P S; Mishchenko, T A; Mitroshina, E V; Koroleva, A V; Chichkov, B N; Panchenko, V Ya; Bagratashvili, V N; Mukhina, I V

    2016-08-01

    We developed and tested new 3D scaffolds for neurotransplantation. Scaffolds of predetermined architectonic were prepared using microstereolithography technique. Scaffolds were highly biocompatible with the nervous tissue cells. In vitro studies showed that the material of fabricated scaffolds is not toxic for dissociated brain cells and promotes the formation of functional neural networks in the matrix. These results demonstrate the possibility of fabrication of tissue-engineering constructs for neurotransplantation based on created scaffolds.

  20. Dynamics of blood flow and thrombus formation in a multi-bypass microfluidic ladder network.

    Science.gov (United States)

    Zilberman-Rudenko, Jevgenia; Sylman, Joanna L; Lakshmanan, Hari H S; McCarty, Owen J T; Maddala, Jeevan

    2017-02-01

    The reaction dynamics of a complex mixture of cells and proteins, such as blood, in branched circulatory networks within the human microvasculature or extravascular therapeutic devices such as extracorporeal oxygenation machine (ECMO) remains ill-defined. In this report we utilize a multi-bypass microfluidics ladder network design with dimensions mimicking venules to study patterns of blood platelet aggregation and fibrin formation under complex shear. Complex blood fluid dynamics within multi-bypass networks under flow were modeled using COMSOL. Red blood cells and platelets were assumed to be non-interacting spherical particles transported by the bulk fluid flow, and convection of the activated coagulation factor II, thrombin, was assumed to be governed by mass transfer. This model served as the basis for predicting formation of local shear rate gradients, stagnation points and recirculation zones as dictated by the bypass geometry. Based on the insights from these models, we were able to predict the patterns of blood clot formation at specific locations in the device. Our experimental data was then used to adjust the model to account for the dynamical presence of thrombus formation in the biorheology of blood flow. The model predictions were then compared to results from experiments using recalcified whole human blood. Microfluidic devices were coated with the extracellular matrix protein, fibrillar collagen, and the initiator of the extrinsic pathway of coagulation, tissue factor. Blood was perfused through the devices at a flow rate of 2 µL/min, translating to physiologically relevant initial shear rates of 300 and 700 s -1 for main channels and bypasses, respectively. Using fluorescent and light microscopy, we observed distinct flow and thrombus formation patterns near channel intersections at bypass points, within recirculation zones and at stagnation points. Findings from this proof-of-principle ladder network model suggest a specific correlation between

  1. A new building block for DNA network formation by self-assembly and polymerase chain reaction.

    Science.gov (United States)

    Bußkamp, Holger; Keller, Sascha; Robotta, Marta; Drescher, Malte; Marx, Andreas

    2014-01-01

    The predictability of DNA self-assembly is exploited in many nanotechnological approaches. Inspired by naturally existing self-assembled DNA architectures, branched DNA has been developed that allows self-assembly to predesigned architectures with dimensions on the nanometer scale. DNA is an attractive material for generation of nanostructures due to a plethora of enzymes which modify DNA with high accuracy, providing a toolbox for many different manipulations to construct nanometer scaled objects. We present a straightforward synthesis of a rigid DNA branching building block successfully used for the generation of DNA networks by self-assembly and network formation by enzymatic DNA synthesis. The Y-shaped 3-armed DNA construct, bearing 3 primer strands is accepted by Taq DNA polymerase. The enzyme uses each arm as primer strand and incorporates the branched construct into large assemblies during PCR. The networks were investigated by agarose gel electrophoresis, atomic force microscopy, dynamic light scattering, and electron paramagnetic resonance spectroscopy. The findings indicate that rather rigid DNA networks were formed. This presents a new bottom-up approach for DNA material formation and might find applications like in the generation of functional hydrogels.

  2. Tolerance-based interaction: a new model targeting opinion formation and diffusion in social networks

    Directory of Open Access Journals (Sweden)

    Alexandru Topirceanu

    2016-01-01

    Full Text Available One of the main motivations behind social network analysis is the quest for understanding opinion formation and diffusion. Previous models have limitations, as they typically assume opinion interaction mechanisms based on thresholds which are either fixed or evolve according to a random process that is external to the social agent. Indeed, our empirical analysis on large real-world datasets such as Twitter, Meme Tracker, and Yelp, uncovers previously unaccounted for dynamic phenomena at population-level, namely the existence of distinct opinion formation phases and social balancing. We also reveal that a phase transition from an erratic behavior to social balancing can be triggered by network topology and by the ratio of opinion sources. Consequently, in order to build a model that properly accounts for these phenomena, we propose a new (individual-level opinion interaction model based on tolerance. As opposed to the existing opinion interaction models, the new tolerance model assumes that individual’s inner willingness to accept new opinions evolves over time according to basic human traits. Finally, by employing discrete event simulation on diverse social network topologies, we validate our opinion interaction model and show that, although the network size and opinion source ratio are important, the phase transition to social balancing is mainly fostered by the democratic structure of the small-world topology.

  3. Selective Deletion of Leptin Signaling in Endothelial Cells Enhances Neointima Formation and Phenocopies the Vascular Effects of Diet-Induced Obesity in Mice.

    Science.gov (United States)

    Hubert, Astrid; Bochenek, Magdalena L; Schütz, Eva; Gogiraju, Rajinikanth; Münzel, Thomas; Schäfer, Katrin

    2017-09-01

    Obesity is associated with elevated circulating leptin levels and hypothalamic leptin resistance. Leptin receptors (LepRs) are expressed on endothelial cells, and leptin promotes neointima formation in a receptor-dependent manner. Our aim was to examine the importance of endothelial LepR (End.LepR) signaling during vascular remodeling and to determine whether the cardiovascular consequences of obesity are because of hyperleptinemia or endothelial leptin resistance. Mice with loxP-flanked LepR alleles were mated with mice expressing Cre recombinase controlled by the inducible endothelial receptor tyrosine kinase promoter. Obesity was induced with high-fat diet. Neointima formation was examined after chemical carotid artery injury. Morphometric quantification revealed significantly greater intimal hyperplasia, neointimal cellularity, and proliferation in End.LepR knockout mice, and similar findings were obtained in obese, hyperleptinemic End.LepR wild-type animals. Analysis of primary endothelial cells confirmed abrogated signal transducer and activator of transcription-3 phosphorylation in response to leptin in LepR knockout and obese LepR wild-type mice. Quantitative PCR, ELISA, and immunofluorescence analyses revealed increased expression and release of endothelin-1 in End.LepR-deficient and LepR-resistant cells, and ET receptor A/B antagonists abrogated their paracrine effects on murine aortic smooth muscle cell proliferation. Reduced expression of peroxisome proliferator-activated receptor-γ and increased nuclear activator protein-1 staining was observed in End.LepR-deficient and LepR-resistant cells, and peroxisome proliferator-activated receptor-γ antagonization increased endothelial endothelin-1 expression. Our findings suggest that intact endothelial leptin signaling limits neointima formation and that obesity represents a state of endothelial leptin resistance. These observations and the identification of endothelin-1 as soluble mediator of the

  4. Analysis of the packet formation process in packet-switched networks

    Science.gov (United States)

    Meditch, J. S.

    Two new queueing system models for the packet formation process in packet-switched telecommunication networks are developed, and their applications in process stability, performance analysis, and optimization studies are illustrated. The first, an M/M/1 queueing system characterization of the process, is a highly aggregated model which is useful for preliminary studies. The second, a marked extension of an earlier M/G/1 model, permits one to investigate stability, performance characteristics, and design of the packet formation process in terms of the details of processor architecture, and hardware and software implementations with processor structure and as many parameters as desired as variables. The two new models together with the earlier M/G/1 characterization span the spectrum of modeling complexity for the packet formation process from basic to advanced.

  5. Meteorological Support Interface Control Working Group (MSICWG) Instrumentation, Data Format, and Networks Document

    Science.gov (United States)

    Brenton, James; Roberts, Barry C.

    2017-01-01

    The purpose of this document is to provide an overview of instrumentation discussed at the Meteorological Interface Control Working Group (MSICWG), a reference for data formats currently used by members of the group, a summary of proposed formats for future use by the group, an overview of the data networks of the group's members. This document will be updated as new systems are introduced, old systems are retired, and when the MSICWG community necessitates a change to the formats. The MSICWG consists of personnel from the National Aeronautics and Space Administration (NASA) Kennedy Space Center (KSC), NASA Marshall Space Flight Center (MSFC), NASA Johnson Space Center (JSC), National Oceanic and Atmospheric Administration National Weather Service Spaceflight Meteorology Group (SMG), and the United States Air Force (USAF) 45th Space Wing and Weather Squadron. The purpose of the group is to coordinate the distribution of weather related data to support NASA space launch related activities.

  6. A biodegradable vascularizing membrane: a feasibility study.

    Science.gov (United States)

    Kaushiva, Anchal; Turzhitsky, Vladimir M; Darmoc, Marissa; Backman, Vadim; Ameer, Guillermo A

    2007-09-01

    Regenerative medicine and in vivo biosensor applications require the formation of mature vascular networks for long-term success. This study investigated whether biodegradable porous membranes could induce the formation of a vascularized fibrous capsule and, if so, the effect of degradation kinetics on neovascularization. Poly(l-lactic acid) (PLLA) and poly(dl-lactic-co-glycolic) acid (PLGA) membranes were created by a solvent casting/salt leaching method. Specifically, PLLA, PLGA 75:25 and PLGA 50:50 polymers were used to vary degradation kinetics. The membranes were designed to have an average 60mum pore diameter, as this pore size has been shown to be optimal for inducing blood vessel formation around nondegradable polymer materials. Membrane samples were imaged by scanning electron microscopy at several time points during in vitro degradation to assess any changes in pore structure. The in vivo performance of the membranes was assessed in Sprague-Dawley rats by measuring vascularization within the fibrous capsule that forms adjacent to implants. The vascular density within 100microm of the membranes was compared with that seen in normal tissue, and to that surrounding the commercially available vascularizing membrane TheraCyte. The hemoglobin content of tissue containing the membranes was measured by four-dimensional elastic light scattering as a novel method to assess tissue perfusion. Results from this study show that slow-degrading membranes induce greater amounts of neovascularization and a thinner fibrous capsule relative to fast degrading membranes. These results may be due both to an initially increased number of macrophages surrounding the slower degrading membranes and to the maintenance of their initial pore structure.

  7. Umbilical Cord Blood-Derived Mononuclear Cells Exhibit Pericyte-Like Phenotype and Support Network Formation of Endothelial Progenitor Cells In Vitro.

    Science.gov (United States)

    Peters, Erica B; Liu, Betty; Christoforou, Nicolas; West, Jennifer L; Truskey, George A

    2015-10-01

    Umbilical cord blood represents a promising cell source for pro-angiogenic therapies. The present study examined the potential of mononuclear cells (MNCs) from umbilical cord blood to support endothelial progenitor cell (EPC) microvessel formation. MNCs were isolated from the cord blood of 20 separate donors and selected for further characterization based upon their proliferation potential and morphological resemblance to human vascular pericytes (HVPs). MNCs were screened for their ability to support EPC network formation using an in vitro assay (Matrigel™) as well as a reductionist, coculture system consisting of no additional angiogenic cytokines beyond those present in serum. In less than 15% of the isolations, we identified a population of highly proliferative MNCs that phenotypically resembled HVPs as assessed by expression of PDGFR-β, NG2, α-SMA, and ephrin-B2. Within a Matrigel™ system, MNCs demonstrated pericyte-like function through colocalization to EPC networks and similar effects as HVPs upon total EPC tubule length (p = 0.95) and number of branch points (p = 0.93). In a reductionist coculture system, MNCs served as pro-angiogenic mural cells by supporting EPC network formation to a significantly greater extent than HVP cocultures, by day 14 of coculture, as evidenced through EPC total tubule length (p < 0.0001) and number of branch points (p < 0.0001). Our findings are significant as we demonstrate mural cell progenitors can be isolated from umbilical cord blood and develop culture conditions to support their use in microvascular tissue engineering applications.

  8. Formation of DNA-network embedding ferromagnetic Cobalt nano-particles

    Science.gov (United States)

    Kanki, Teruo; Tanaka, Hidekazu; Shirakawa, Hideaki; Sacho, Yu; Taniguchi, Masateru; Lee, Hea-Yeon; Kawai, Tomoji; Kang, Nam-Jung; Chen, Jinwoo

    2002-03-01

    Formation of DNA-network embedding ferromagnetic Cobalt nano-particles T. Kanki, Hidekazu. Tanaka, H. Shirakawa, Y. Sacho, M. Taniguchi, H. Lee, T. Kawai The Institute of Scientific and Industrial Research, Osaka University, Japan and Nam-Jung Kang, Jinwoo Chen Korea Advanced Institute of Science and Technology (KAIST), Korea DNA can be regarded as a naturally occurring and highly specific functional biopolymer and as a fine nano-wire. Moreover, it was found that large-scale DNA networks can be fabricated on mica surfaces. By using this network structure, we can expect to construct nano-scale assembly of functional nano particle, for example ferromagnetic Co nano particles, toward nano scale spin-electronics based on DNA circuits. When we formed DNA network by 250mg/ml DNA solution of poly(dG)-poly(dC) including ferromagnetic Co nano particles (diameter of 12nm), we have conformed the DNA network structure embedding Co nano-particles (height of about 12nm) by atomic force microscopy. On the other hand, we used 100mg/ml DNA solution, DNA can not connect each other, and many Co nano-particles exist without being embedded.

  9. NETWORK FOLKLORE AND ITS ROLE IN THE FORMATION OF A COLLECTIVE COGNITIVE SPACE

    Directory of Open Access Journals (Sweden)

    Anastasija Belovodskaja

    2014-04-01

    Full Text Available The global implementation of information-communicative technologies into every sphere of human activity is being accompanied by the emergence of new forms of communication, le­ading to inevitable changes in the means of both the representation and reception of information. In this respect, the field of interest encompasses research into modern anonymous network creative writing, which, as a result of the technological qualities of the Internet space, produces such texts that require particular skills in both comprehension and reproduction. In turn, the products of network folklore, as they spontaneously spread on the Internet, acquire the status of particular signs of a precedent nature. At the same time, the very nature of anonymous network creative writing—amusing and colloquial—raises the attractiveness of such texts and facilitates their reception, allowing them to be used for manipulative aims. The fact that such network folklore can influence the process of idea-formation in society is predetermined by the fact that, by definition, it is the milieu where collective representations are condensed and transmitted. Thus, network folklore is in the focus of attention not only in folklore studies, but is extremely topical for research in such fields as cognitive science, linguistic-cultural studies, public relations, speech effect, and any others which take interest in the processes of keeping, receiving, and transmitting information.

  10. Divergent effects of 17-β-estradiol on human vascular smooth muscle and endothelial cell function diminishes TNF-α-induced neointima formation

    International Nuclear Information System (INIS)

    Nintasen, Rungrat; Riches, Kirsten; Mughal, Romana S.; Viriyavejakul, Parnpen; Chaisri, Urai; Maneerat, Yaowapa; Turner, Neil A.; Porter, Karen E.

    2012-01-01

    Highlights: ► TNF-α augments neointimal hyperplasia in human saphenous vein. ► TNF-α induces detrimental effects on endothelial and smooth muscle cell function. ► Estradiol exerts modulatory effects on TNF-induced vascular cell functions. ► The modulatory effects of estradiol are discriminatory and cell-type specific. -- Abstract: Coronary heart disease (CHD) is a condition characterized by increased levels of proinflammatory cytokines, including tumor necrosis factor-α (TNF-α). TNF-α can induce vascular endothelial cell (EC) and smooth muscle cell (SMC) dysfunction, central events in development of neointimal lesions. The reduced incidence of CHD in young women is believed to be due to the protective effects of estradiol (E2). We therefore investigated the effects of TNF-α on human neointima formation and SMC/EC functions and any modulatory effects of E2. Saphenous vein (SV) segments were cultured in the presence of TNF-α (10 ng/ml), E2 (2.5 nM) or both in combination. Neointimal thickening was augmented by incubation with TNF-α, an effect that was abolished by co-culture with E2. TNF-α increased SV–SMC proliferation in a concentration-dependent manner that was optimal at 10 ng/ml (1.5-fold increase), and abolished by E2 at all concentrations studied (1–50 nM). Surprisingly, E2 itself at low concentrations (1 and 5 nM) stimulated SV–SMC proliferation to a level comparable to that of TNF-α alone. SV–EC migration was significantly impaired by TNF-α (42% of control), and co-culture with E2 partially restored the ability of SV–EC to migrate and repair the wound. In contrast, TNF-α increased SV–SMC migration by 1.7-fold, an effect that was completely reversed by co-incubation with E2. Finally, TNF-α potently induced ICAM-1 and VCAM-1 expression in both SV–EC and SV–SMC. However there was no modulation by E2 in either cell-type. In conclusion, TNF-α induced SV neointima formation, increased SMC proliferation and migration, impaired

  11. Divergent effects of 17-{beta}-estradiol on human vascular smooth muscle and endothelial cell function diminishes TNF-{alpha}-induced neointima formation

    Energy Technology Data Exchange (ETDEWEB)

    Nintasen, Rungrat [Division of Cardiovascular Medicine, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT (United Kingdom); Multidisciplinary Cardiovascular Research Center (MCRC), University of Leeds, Leeds LS2 9JT (United Kingdom); Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University (Thailand); Riches, Kirsten; Mughal, Romana S. [Division of Cardiovascular Medicine, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT (United Kingdom); Multidisciplinary Cardiovascular Research Center (MCRC), University of Leeds, Leeds LS2 9JT (United Kingdom); Viriyavejakul, Parnpen; Chaisri, Urai; Maneerat, Yaowapa [Department of Tropical Pathology, Faculty of Tropical Medicine, Mahidol University (Thailand); Turner, Neil A. [Division of Cardiovascular Medicine, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT (United Kingdom); Multidisciplinary Cardiovascular Research Center (MCRC), University of Leeds, Leeds LS2 9JT (United Kingdom); Porter, Karen E., E-mail: medkep@leeds.ac.uk [Division of Cardiovascular Medicine, Leeds Institute of Genetics, Health and Therapeutics, University of Leeds, Leeds LS2 9JT (United Kingdom); Multidisciplinary Cardiovascular Research Center (MCRC), University of Leeds, Leeds LS2 9JT (United Kingdom)

    2012-04-20

    Highlights: Black-Right-Pointing-Pointer TNF-{alpha} augments neointimal hyperplasia in human saphenous vein. Black-Right-Pointing-Pointer TNF-{alpha} induces detrimental effects on endothelial and smooth muscle cell function. Black-Right-Pointing-Pointer Estradiol exerts modulatory effects on TNF-induced vascular cell functions. Black-Right-Pointing-Pointer The modulatory effects of estradiol are discriminatory and cell-type specific. -- Abstract: Coronary heart disease (CHD) is a condition characterized by increased levels of proinflammatory cytokines, including tumor necrosis factor-{alpha} (TNF-{alpha}). TNF-{alpha} can induce vascular endothelial cell (EC) and smooth muscle cell (SMC) dysfunction, central events in development of neointimal lesions. The reduced incidence of CHD in young women is believed to be due to the protective effects of estradiol (E2). We therefore investigated the effects of TNF-{alpha} on human neointima formation and SMC/EC functions and any modulatory effects of E2. Saphenous vein (SV) segments were cultured in the presence of TNF-{alpha} (10 ng/ml), E2 (2.5 nM) or both in combination. Neointimal thickening was augmented by incubation with TNF-{alpha}, an effect that was abolished by co-culture with E2. TNF-{alpha} increased SV-SMC proliferation in a concentration-dependent manner that was optimal at 10 ng/ml (1.5-fold increase), and abolished by E2 at all concentrations studied (1-50 nM). Surprisingly, E2 itself at low concentrations (1 and 5 nM) stimulated SV-SMC proliferation to a level comparable to that of TNF-{alpha} alone. SV-EC migration was significantly impaired by TNF-{alpha} (42% of control), and co-culture with E2 partially restored the ability of SV-EC to migrate and repair the wound. In contrast, TNF-{alpha} increased SV-SMC migration by 1.7-fold, an effect that was completely reversed by co-incubation with E2. Finally, TNF-{alpha} potently induced ICAM-1 and VCAM-1 expression in both SV-EC and SV-SMC. However there

  12. gamma-tocopherol, but not alpha-tocopherol, potently inhibits neointimal formation induced by vascular injury in insulin resistant rats.

    Science.gov (United States)

    Takahashi, Katsuaki; Komaru, Tatsuya; Takeda, Satoru; Takeda, Morihiko; Koshida, Ryoji; Nakayama, Masaharu; Kokusho, Yasunori; Kawakami, Yuki; Yamaguchi, Nobuhiro; Miyazawa, Teruo; Shimokawa, Hiroaki; Shirato, Kunio

    2006-09-01

    Insulin resistance may enhance the neointima formation via increased oxidative stress. However, clinical trials investigating the benefit of antioxidant therapy with alpha-tocopherol showed negative results. Recent studies showed that chemical characteristics of gamma-tocopherol are distinct from those of alpha-tocopherol. We hypothesized that gamma-tocopherol is superior to alpha-tocopherol in preventing the neointima growth after arterial injury in insulin resistance. Male rats were fed with standard chow or a high fructose diet for induction of insulin resistance. Thereafter, the left carotid artery was injured with a balloon catheter. After 2 weeks, the carotid arteries were harvested and histomorphometrically analyzed. The neointima-media ratio of the injured artery was significantly greater in insulin resistance group (n=8, 1.33+/-0.12) than in normal group (n=10, 0.76+/-0.11, pinsulin resistance group), while alpha-tocopherol was without effect (n=7, 1.08+/-0.14). The quantification of plasma phosphatidylcholine hydroperoxide, an indicator of systemic oxidative stress, and dihydroethidium fluorescence staining of the carotid artery, an indicator of the local superoxide production, showed that oxidative stress in the systemic circulation and local arterial tissue was increased in insulin resistance. Both tocopherols decreased plasma phosphatidylcholine hydroperoxide, but failed to suppress the superoxide production in the carotid arteries. Increased 3-nitrotyrosine in neointima by insulin resistance was greatly reduced only by gamma-tocopherol. In conclusion, gamma-tocopherol, but not alpha-tocopherol, reduces the neointima proliferation in insulin resistance, independently of its effects on superoxide production. The beneficial effect may be related with its inhibitory effects on nitrosative stress.

  13. Experimental demonstration of large capacity WSDM optical access network with multicore fibers and advanced modulation formats.

    Science.gov (United States)

    Li, Borui; Feng, Zhenhua; Tang, Ming; Xu, Zhilin; Fu, Songnian; Wu, Qiong; Deng, Lei; Tong, Weijun; Liu, Shuang; Shum, Perry Ping

    2015-05-04

    Towards the next generation optical access network supporting large capacity data transmission to enormous number of users covering a wider area, we proposed a hybrid wavelength-space division multiplexing (WSDM) optical access network architecture utilizing multicore fibers with advanced modulation formats. As a proof of concept, we experimentally demonstrated a WSDM optical access network with duplex transmission using our developed and fabricated multicore (7-core) fibers with 58.7km distance. As a cost-effective modulation scheme for access network, the optical OFDM-QPSK signal has been intensity modulated on the downstream transmission in the optical line terminal (OLT) and it was directly detected in the optical network unit (ONU) after MCF transmission. 10 wavelengths with 25GHz channel spacing from an optical comb generator are employed and each wavelength is loaded with 5Gb/s OFDM-QPSK signal. After amplification, power splitting, and fan-in multiplexer, 10-wavelength downstream signal was injected into six outer layer cores simultaneously and the aggregation downstream capacity reaches 300 Gb/s. -16 dBm sensitivity has been achieved for 3.8 × 10-3 bit error ratio (BER) with 7% Forward Error Correction (FEC) limit for all wavelengths in every core. Upstream signal from ONU side has also been generated and the bidirectional transmission in the same core causes negligible performance degradation to the downstream signal. As a universal platform for wired/wireless data access, our proposed architecture provides additional dimension for high speed mobile signal transmission and we hence demonstrated an upstream delivery of 20Gb/s per wavelength with QPSK modulation formats using the inner core of MCF emulating a mobile backhaul service. The IQ modulated data was coherently detected in the OLT side. -19 dBm sensitivity has been achieved under the FEC limit and more than 18 dB power budget is guaranteed.

  14. Dynamic adaption of vascular morphology

    DEFF Research Database (Denmark)

    Okkels, Fridolin; Jacobsen, Jens Christian Brings

    2012-01-01

    The structure of vascular networks adapts continuously to meet changes in demand of the surrounding tissue. Most of the known vascular adaptation mechanisms are based on local reactions to local stimuli such as pressure and flow, which in turn reflects influence from the surrounding tissue. Here ...

  15. Precise Localization and Formation Control of Swarm Robots via Wireless Sensor Networks

    Directory of Open Access Journals (Sweden)

    Han Wu

    2014-01-01

    Full Text Available Precise localization and formation control are one of the key technologies to achieve coordination and control of swarm robots, which is also currently a bottleneck for practical applications of swarm robotic systems. Aiming at overcoming the limited individual perception and the difficulty of achieving precise localization and formation, a localization approach combining dead reckoning (DR with wireless sensor network- (WSN- based methods is proposed in this paper. Two kinds of WSN localization technologies are adopted in this paper, that is, ZigBee-based RSSI (received signal strength indication global localization and electronic tag floors for calibration of local positioning. First, the DR localization information is combined with the ZigBee-based RSSI position information using the Kalman filter method to achieve precise global localization and maintain the robot formation. Then the electronic tag floors provide the robots with their precise coordinates in some local areas and enable the robot swarm to calibrate its formation by reducing the accumulated position errors. Hence, the overall performance of localization and formation control of the swarm robotic system is improved. Both of the simulation results and the experimental results on a real schematic system are given to demonstrate the success of the proposed approach.

  16. Ising-based model of opinion formation in a complex network of interpersonal interactions

    Science.gov (United States)

    Grabowski, A.; Kosiński, R. A.

    2006-03-01

    In our work the process of opinion formation in the human population, treated as a scale-free network, is modeled and investigated numerically. The individuals (nodes of the network) are characterized by their authorities, which influence the interpersonal interactions in the population. Hierarchical, two-level structures of interpersonal interactions and spatial localization of individuals are taken into account. The effect of the mass media, modeled as an external stimulation acting on the social network, on the process of opinion formation is investigated. It was found that in the time evolution of opinions of individuals critical phenomena occur. The first one is observed in the critical temperature of the system TC and is connected with the situation in the community, which may be described by such quantifiers as the economic status of people, unemployment or crime wave. Another critical phenomenon is connected with the influence of mass media on the population. As results from our computations, under certain circumstances the mass media can provoke critical rebuilding of opinions in the population.

  17. Unravelling the secret of seed-based gels in water: the nanoscale 3D network formation.

    Science.gov (United States)

    Samateh, Malick; Pottackal, Neethu; Manafirasi, Setareh; Vidyasagar, Adiyala; Maldarelli, Charles; John, George

    2018-05-09

    Chia (Salvia hispanica) and basil (Ocimum basilicum) seeds have the intrinsic ability to form a hydrogel concomitant with moisture-retention, slow releasing capability and proposed health benefits such as curbing diabetes and obesity by delaying digestion process. However, the underlying mode of gelation at nanoscopic level is not clearly explained or explored. The present study elucidates and corroborates the hypothesis that the gelling behavior of such seeds is due to their nanoscale 3D-network formation. The preliminary study revealed the influence of several conditions like polarity, pH and hydrophilicity/hydrophobicity on fiber extrusion from the seeds which leads to gelation. Optical microscopic analysis clearly demonstrated bundles of fibers emanating from the seed coat while in contact with water, and live growth of fibers to form 3D network. Scanning electron microscope (SEM) and transmission electron microscope (TEM) studies confirmed 3D network formation with fiber diameters ranging from 20 to 50 nm.

  18. C60-pentacene network formation by 2-D co-crystallization.

    Science.gov (United States)

    Jin, Wei; Dougherty, Daniel B; Cullen, William G; Robey, Steven; Reutt-Robey, Janice E

    2009-09-01

    We report experiments highlighting the mechanistic role of mobile pentacene precursors in the formation of a network C(60)-pentacene co-crystalline structure on Ag(111). This co-crystalline arrangement was first observed by low temperature scanning tunneling microscopy (STM) by Zhang et al. (Zhang, H. L.; Chen, W.; Huang, H.; Chen, L.; Wee, A. T. S. J. Am. Chem. Soc. 2008, 130, 2720-2721). We now show that this structure forms readily at room temperature from a two-dimensional (2-D) mixture. Pentacene, evaporated onto Ag(111) to coverages of 0.4-1.0 ML, produces a two-dimensional (2-D) gas. Subsequently deposited C(60) molecules combine with the pentacene 2-D gas to generate a network structure, consisting of chains of close-packed C(60) molecules, spaced by individual C(60) linkers and 1 nm x 2.5 nm pores containing individual pentacene molecules. Spontaneous formation of this stoichiometric (C(60))(4)-pentacene network from a range of excess pentacene surface coverage (0.4 to 1.0 ML) indicates a self-limiting assembly process. We refine the structure model for this phase and discuss the generality of this co-crystallization mechanism.

  19. EXPLORING THE RELATIONSHIPS AMONG SOCIAL BENEFITS, ONLINE SOCIAL NETWORK DEPENDENCY, SATISFACTION, AND YOUTH’S HABIT FORMATION

    Directory of Open Access Journals (Sweden)

    Tran Van Dat

    2015-12-01

    Full Text Available Online social network is one of the biggest Internet phenomenon, which has attracted the interest of many marketers and psychologists who wanted to understand social network users’ behavior. Recognizing the lack of theoretical and empirical attention that has been given to this field, especially in Vietnam market, this study was conducted to examine the relationships among social benefits, online social network dependency, satisfaction, and youth’s habit formation in the context of Facebook. The findings of the study of 200 Facebook users indicated that the interrelationship among four factors of social benefits, online social network dependency, satisfaction, and habit formation affect each other. Indeed, dependency on online social network among the youth whose age ranged from 16 to 24 years old is significantly affected by social benefits factor and leads to the formation of habit. In addition, satisfaction plays a role in determining habitual Facebook use. This paper discusses theoretical and practical implication in marketing and psychology field.

  20. Formative research on the primo vascular system and acceptance by the korean scientific community: the gap between creative basic science and practical convergence technology.

    Science.gov (United States)

    Kim, Hoon Gi

    2013-12-01

    The purpose of this study was to trace the formative process of primo vascular system (PVS) research over the past decade and to describe the characteristics of the Korean scientific community. By publishing approximately 30 papers in journals ranking in the Science Citation Index (Expanded), the PVS research team actively convinced domestic and international scientists of the anatomical existence of the PVS and its possible application to Korean and Western medicine. In addition, by sharing the PVS observation technique, the team promoted the dissemination and further pursuit of the research. In 2012, however, PVS researchers performed smaller scale research without advancing to a higher level as compared to the early days. The main reasons were found to be the Korean Research and Development policy of supporting creative, small-scale basic research and applied research of Western scientific fields that promised potentially greater success on an extensive scale; the indifference concerning, and the disbelief in, the existence of a new circulatory system were shown by the Western medical community. In addition, the Oriental medical community was apathetic about working with the PVS team. Professors Kwang-Sup Soh and Byung-Cheon Lee were the prime movers of PVS research under difficult conditions. Spurred by their belief in the existence and significance of the PVS, they continued with their research despite insufficient experimental data. The Korean scientific community is not ready to promote the Korea-oriented creative field of the PVS team. Copyright © 2013. Published by Elsevier B.V.

  1. Robust Drones Formation Control in 5G Wireless Sensor Network Using mmWave

    Directory of Open Access Journals (Sweden)

    Shan Meng

    2018-01-01

    Full Text Available The drones formation control in 5G wireless sensor network is discussed. The base station (BS is used to receive backhaul position signals from the lead drone in formation and launches the beam to the lead one as the fronthaul flying signal enhancement. It is a promising approach to raise the formation strength of drones during flight control. The BS can transform the direction of the antennas and transmit energy to the lead drone that could widely enlarge the number of the receivers and increase the transmission speed of the data links. The millimeter-Wave (mmWave communication system offers new opportunities to meet this requirement owing to the tremendous amount of available spectrums. However, the massive non-line-of-sight (NLoS transmission and the site constraints in urban environment are severely challenging the conventional deploying terrestrial low power nodes (LPNs. Simulation experiments have been performed to verify the availability and effectiveness of mmWave in 5G wireless sensor network.

  2. Joint OSNR monitoring and modulation format identification in digital coherent receivers using deep neural networks.

    Science.gov (United States)

    Khan, Faisal Nadeem; Zhong, Kangping; Zhou, Xian; Al-Arashi, Waled Hussein; Yu, Changyuan; Lu, Chao; Lau, Alan Pak Tao

    2017-07-24

    We experimentally demonstrate the use of deep neural networks (DNNs) in combination with signals' amplitude histograms (AHs) for simultaneous optical signal-to-noise ratio (OSNR) monitoring and modulation format identification (MFI) in digital coherent receivers. The proposed technique automatically extracts OSNR and modulation format dependent features of AHs, obtained after constant modulus algorithm (CMA) equalization, and exploits them for the joint estimation of these parameters. Experimental results for 112 Gbps polarization-multiplexed (PM) quadrature phase-shift keying (QPSK), 112 Gbps PM 16 quadrature amplitude modulation (16-QAM), and 240 Gbps PM 64-QAM signals demonstrate OSNR monitoring with mean estimation errors of 1.2 dB, 0.4 dB, and 1 dB, respectively. Similarly, the results for MFI show 100% identification accuracy for all three modulation formats. The proposed technique applies deep machine learning algorithms inside standard digital coherent receiver and does not require any additional hardware. Therefore, it is attractive for cost-effective multi-parameter estimation in next-generation elastic optical networks (EONs).

  3. Identification of cyst nematode B-type CLE peptides and modulation of the vascular stem cell pathway for feeding cell formation.

    Directory of Open Access Journals (Sweden)

    Xiaoli Guo

    2017-02-01

    Full Text Available Stem cell pools in the SAM (shoot apical meristem, RAM (root apical meristem and vascular procambium/cambium are regulated by CLE-receptor kinase-WOX signaling modules. Previous data showed that cyst nematode CLE-like effector proteins delivered into host cells through a stylet, act as ligand mimics of plant A-type CLE peptides and are pivotal for successful parasitism. Here we report the identification of a new class of CLE peptides from cyst nematodes with functional similarity to the B-type CLE peptide TDIF (tracheary element differentiation inhibitory factor encoded by the CLE41 and CLE44 genes in Arabidopsis. We further demonstrate that the TDIF-TDR (TDIF receptor-WOX4 pathway, which promotes procambial meristem cell proliferation, is involved in beet cyst nematode Heterodera schachtii parasitism. We observed activation of the TDIF pathway in developing feeding sites, reduced nematode infection in cle41 and tdr-1 wox4-1 mutants, and compromised syncytium size in cle41, tdr-1, wox4-1 and tdr-1 wox4-1 mutants. By qRT-PCR and promoter:GUS analyses, we showed that the expression of WOX4 is decreased in a clv1-101 clv2-101 rpk2-5 mutant, suggesting that WOX4 is a potential downstream target of nematode CLEs. Exogenous treatment with both nematode A-type and B-type CLE peptides induced massive cell proliferation in wild type roots, suggesting that the two types of CLEs may regulate cell proliferation during feeding site formation. These findings highlight an important role of the procambial cell proliferation pathway in cyst nematode feeding site formation.

  4. Macrophage conditioned medium induced cellular network formation in MCF-7 cells through enhanced tunneling nanotube formation and tunneling nanotube mediated release of viable cytoplasmic fragments

    International Nuclear Information System (INIS)

    Patheja, Pooja; Sahu, Khageswar

    2017-01-01

    Infiltrating macrophages in tumor microenvironment, through their secreted cytokines and growth factors, regulate several processes of cancer progression such as cancer cell survival, proliferation, invasion, metastasis and angiogenesis. Recently, intercellular cytoplasmic bridges between cancer cells referred as tunneling nanotubes (TNTs) have been recognized as novel mode of intercellular communication between cancer cells. In this study, we investigated the effect of inflammatory mediators present in conditioned medium derived from macrophages on the formation of TNTs in breast adenocarcinoma cells MCF-7. Results show that treatment with macrophage conditioned medium (MφCM) not only enhanced TNT formation between cells but also stimulated the release of independently migrating viable cytoplasmic fragments, referred to as microplasts, from MCF-7 cells. Time lapse microscopy revealed that microplasts were released from parent cancer cells in extracellular space through formation of TNT-like structures. Mitochondria, vesicles and cytoplasm could be transferred from parent cell body to microplasts through connecting TNTs. The microplasts could also be resorbed into the parent cell body by retraction of the connecting TNTs. Microplast formation inhibited in presence cell migration inhibitor, cytochalasin-B. Notably by utilizing migratory machinery within microplasts, distantly located MCF-7 cells formed several TNT based intercellular connections, leading to formation of physically connected network of cells. Together, these results demonstrate novel role of TNTs in microplast formation, novel modes of TNT formation mediated by microplasts and stimulatory effect of MφCM on cellular network formation in MCF-7 cells mediated through enhanced TNT and microplast formation.

  5. Macrophage conditioned medium induced cellular network formation in MCF-7 cells through enhanced tunneling nanotube formation and tunneling nanotube mediated release of viable cytoplasmic fragments

    Energy Technology Data Exchange (ETDEWEB)

    Patheja, Pooja, E-mail: pooja.patheja8@gmail.com [Laser Biomedical Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India); Homi Bhabha National Institute, Training School Complex, Anushaktinagar, Mumbai 400094, Maharashtra (India); Sahu, Khageswar [Laser Biomedical Applications Section, Raja Ramanna Centre for Advanced Technology, Indore 452013, Madhya Pradesh (India)

    2017-06-15

    Infiltrating macrophages in tumor microenvironment, through their secreted cytokines and growth factors, regulate several processes of cancer progression such as cancer cell survival, proliferation, invasion, metastasis and angiogenesis. Recently, intercellular cytoplasmic bridges between cancer cells referred as tunneling nanotubes (TNTs) have been recognized as novel mode of intercellular communication between cancer cells. In this study, we investigated the effect of inflammatory mediators present in conditioned medium derived from macrophages on the formation of TNTs in breast adenocarcinoma cells MCF-7. Results show that treatment with macrophage conditioned medium (MφCM) not only enhanced TNT formation between cells but also stimulated the release of independently migrating viable cytoplasmic fragments, referred to as microplasts, from MCF-7 cells. Time lapse microscopy revealed that microplasts were released from parent cancer cells in extracellular space through formation of TNT-like structures. Mitochondria, vesicles and cytoplasm could be transferred from parent cell body to microplasts through connecting TNTs. The microplasts could also be resorbed into the parent cell body by retraction of the connecting TNTs. Microplast formation inhibited in presence cell migration inhibitor, cytochalasin-B. Notably by utilizing migratory machinery within microplasts, distantly located MCF-7 cells formed several TNT based intercellular connections, leading to formation of physically connected network of cells. Together, these results demonstrate novel role of TNTs in microplast formation, novel modes of TNT formation mediated by microplasts and stimulatory effect of MφCM on cellular network formation in MCF-7 cells mediated through enhanced TNT and microplast formation.

  6. Aperiodic dynamics in a deterministic adaptive network model of attitude formation in social groups

    Science.gov (United States)

    Ward, Jonathan A.; Grindrod, Peter

    2014-07-01

    Adaptive network models, in which node states and network topology coevolve, arise naturally in models of social dynamics that incorporate homophily and social influence. Homophily relates the similarity between pairs of nodes' states to their network coupling strength, whilst social influence causes coupled nodes' states to convergence. In this paper we propose a deterministic adaptive network model of attitude formation in social groups that includes these effects, and in which the attitudinal dynamics are represented by an activato-inhibitor process. We illustrate that consensus, corresponding to all nodes adopting the same attitudinal state and being fully connected, may destabilise via Turing instability, giving rise to aperiodic dynamics with sensitive dependence on initial conditions. These aperiodic dynamics correspond to the formation and dissolution of sub-groups that adopt contrasting attitudes. We discuss our findings in the context of cultural polarisation phenomena. Social influence. This reflects the fact that people tend to modify their behaviour and attitudes in response to the opinions of others [22-26]. We model social influence via diffusion: agents adjust their state according to a weighted sum (dictated by the evolving network) of the differences between their state and the states of their neighbours. Homophily. This relates the similarity of individuals' states to their frequency and strength of interaction [27]. Thus in our model, homophily drives the evolution of the weighted ‘social' network. A precise formulation of our model is given in Section 2. Social influence and homophily underpin models of social dynamics [21], which cover a wide range of sociological phenomena, including the diffusion of innovations [28-32], complex contagions [33-36], collective action [37-39], opinion dynamics [19,20,40,10,11,13,15,41,16], the emergence of social norms [42-44], group stability [45], social differentiation [46] and, of particular relevance

  7. Domain wall network as QCD vacuum and the chromomagnetic trap formation under extreme conditions

    International Nuclear Information System (INIS)

    Nedelko, Sergei N.; Voronin, Vladimir E.

    2015-01-01

    The ensemble of Euclidean gluon field configurations represented by the domain wall network is considered. A single domain wall is given by the sine-Gordon kink for the angle between chromomagnetic and chromoelectric components of the gauge field. The domain wall separates the regions with Abelian self-dual and anti-self-dual fields. The network of the domain wall defects is introduced as a combination of multiplicative and additive superpositions of kinks. The character of the spectrum and eigenmodes of color-charged fluctuations in the presence of the domain wall network is discussed. Conditions for the formation of a stable thick domain wall junction (the chromomagnetic trap) during heavy-ion collisions are discussed, and the spectrum of color-charged quasi-particles inside the trap is evaluated. An important observation is the existence of the critical size L c of a single trap stable against gluon tachyonic modes. The size L c is related to the value of gluon condensate left angle g 2 F 2 right angle. The growth of large lumps of merged chromomagnetic traps and the concept of the confinement-deconfinement transition in terms of the ensemble of domain wall networks are outlined. (orig.)

  8. Becoming popular: interpersonal emotion regulation predicts relationship formation in real life social networks

    Science.gov (United States)

    Niven, Karen; Garcia, David; van der Löwe, Ilmo; Holman, David; Mansell, Warren

    2015-01-01

    Building relationships is crucial for satisfaction and success, especially when entering new social contexts. In the present paper, we investigate whether attempting to improve others’ feelings helps people to make connections in new networks. In Study 1, a social network study following new networks of people for a 12-week period indicated that use of interpersonal emotion regulation (IER) strategies predicted growth in popularity, as indicated by other network members’ reports of spending time with the person, in work and non-work interactions. In Study 2, linguistic analysis of the tweets from over 8000 Twitter users from formation of their accounts revealed that use of IER predicted greater popularity in terms of the number of followers gained. However, not all types of IER had positive effects. Behavioral IER strategies (which use behavior to reassure or comfort in order to regulate affect) were associated with greater popularity, while cognitive strategies (which change a person’s thoughts about his or her situation or feelings in order to regulate affect) were negatively associated with popularity. Our findings have implications for our understanding of how new relationships are formed, highlighting the important the role played by intentional emotion regulatory processes. PMID:26483718

  9. Becoming popular: Interpersonal emotion regulation predicts relationship formation in real life social networks

    Directory of Open Access Journals (Sweden)

    Karen eNiven

    2015-09-01

    Full Text Available Building relationships is crucial for satisfaction and success, especially when entering new social contexts. In the present paper, we investigate whether attempting to improve others’ feelings helps people to make connections in new networks. In Study 1, a social network study following new networks of people for a twelve-week period indicated that use of interpersonal emotion regulation (IER strategies predicted growth in popularity, as indicated by other network members’ reports of spending time with the person, in work and non-work interactions. In Study 2, linguistic analysis of the tweets from over 8000 Twitter users from formation of their accounts revealed that use of IER predicted greater popularity in terms of the number of followers gained. However, not all types of IER had positive effects. Behavioral IER strategies (which use behavior to reassure or comfort in order to regulate affect were associated with greater popularity, while cognitive strategies (which change a person’s thoughts about his or her situation or feelings in order to regulate affect were negatively associated with popularity. Our findings have implications for our understanding of how new relationships are formed, highlighting the important the role played by intentional emotion regulatory processes.

  10. Social factors shaping the formation of a multi-stakeholder trails network group for the Monongahela National Forest, West Virginia

    Science.gov (United States)

    Karen Robinson; Steven Selin; Chad Pierskalla

    2009-01-01

    This paper reports the results and management implications of a longitudinal research study examining the social factors affecting the formation of a trails network advisory group for the Monongahela National Forest (MNF) in West Virginia. A collaborative process of creating an MNF trails network with input from local users and stakeholders has been largely...

  11. Formation of nano-hydroxyapatite crystal in situ in chitosan-pectin polyelectrolyte complex network

    International Nuclear Information System (INIS)

    Li Junjie; Zhu Dunwan; Yin Jianwei; Liu Yuxi; Yao Fanglian; Yao Kangde

    2010-01-01

    Hydroxyapatite (HA)/polysaccharide composites have been widely used in bone tissue engineering due to their chemical similarity to natural bone. Polymer matrix-mediated synthesis of nano-hydroxyapatite is one of the simplest models for biomimetic. In this article, the nano-hydroxyapatite/chitosan-pectin (nHCP) composites were prepared through in situ mineralization of hydroxyapatite in chitosan-pectin polyelectrolyte complex (PEC) network. The formation processes of nHCP were investigated by X-ray diffraction (XRD) analysis. The interactions between nHA crystal and chitosan-pectin PEC networks were studied using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The morphology and structure of nHA crystal were characterized by XRD and Transmission Electron Microscope (TEM). Results suggested that the interfacial interactions between nano-hydroxyapatite crystal and chitosan-pectin PEC network assist the site specific nucleation and growth of nHA nanoparticles. The nHA crystals grow along the c-axis. In this process, pH value is the main factor to control the nucleation and growth of nHA crystal in chitosan-pectin PEC networks, because both the interactions' strength between nHA crystal and chitosan-pectin and diffusion rate of inorganic ions depend on the pH value of the reaction system. Apart from the pH value, the chitosan/pectin ratio and [Ca 2+ ] also take important effects on the formation of nHA crystal. An effective way to control the size of nHA crystal is to adjust the content of pectin and [Ca 2+ ]. It is interesting that the Zeta potential of nHCP composites is about - 30 mV when the chitosan/pectin ratio ≤ 1:1, and the dispersion solution of nHCP composites has higher stability, which provides the possibility to prepare 3D porous scaffolds with nHCP for bone tissue engineering.

  12. GDTN: Genome-Based Delay Tolerant Network Formation in Heterogeneous 5G Using Inter-UA Collaboration.

    Science.gov (United States)

    You, Ilsun; Sharma, Vishal; Atiquzzaman, Mohammed; Choo, Kim-Kwang Raymond

    2016-01-01

    With a more Internet-savvy and sophisticated user base, there are more demands for interactive applications and services. However, it is a challenge for existing radio access networks (e.g. 3G and 4G) to cope with the increasingly demanding requirements such as higher data rates and wider coverage area. One potential solution is the inter-collaborative deployment of multiple radio devices in a 5G setting designed to meet exacting user demands, and facilitate the high data rate requirements in the underlying networks. These heterogeneous 5G networks can readily resolve the data rate and coverage challenges. Networks established using the hybridization of existing networks have diverse military and civilian applications. However, there are inherent limitations in such networks such as irregular breakdown, node failures, and halts during speed transmissions. In recent years, there have been attempts to integrate heterogeneous 5G networks with existing ad hoc networks to provide a robust solution for delay-tolerant transmissions in the form of packet switched networks. However, continuous connectivity is still required in these networks, in order to efficiently regulate the flow to allow the formation of a robust network. Therefore, in this paper, we present a novel network formation consisting of nodes from different network maneuvered by Unmanned Aircraft (UA). The proposed model utilizes the features of a biological aspect of genomes and forms a delay tolerant network with existing network models. This allows us to provide continuous and robust connectivity. We then demonstrate that the proposed network model has an efficient data delivery, lower overheads and lesser delays with high convergence rate in comparison to existing approaches, based on evaluations in both real-time testbed and simulation environment.

  13. Effects of Hofmeister salt series on gluten network formation: Part I. Cation series.

    Science.gov (United States)

    Tuhumury, H C D; Small, D M; Day, L

    2016-12-01

    Different cationic salts were used to investigate the effects of the Hofmeister salt series on gluten network formation. The effects of cationic salts on wheat flour dough mixing properties, the rheological and the chemical properties of the gluten extracted from the dough with different respective salts, were investigated. The specific influence of different cationic salts on the gluten structure formation during dough mixing, compared to the sodium ion, were determined. The effects of different cations on dough and gluten of different flours mostly followed the Hofmeister series (NH4(+), K(+), Na(+), Mg(2+) and Ca(2+)). The impacts of cations on gluten structure and dough rheology at levels tested were relatively small. Therefore, the replacement of sodium from a technological standpoint is possible, particularly by monovalent cations such as NH4(+), or K(+). However the levels of replacement need to take into account sensory attributes of the cationic salts. Copyright © 2016 Elsevier Ltd. All rights reserved.

  14. Generating functional analysis of complex formation and dissociation in large protein interaction networks

    International Nuclear Information System (INIS)

    Coolen, A C C; Rabello, S

    2009-01-01

    We analyze large systems of interacting proteins, using techniques from the non-equilibrium statistical mechanics of disordered many-particle systems. Apart from protein production and removal, the most relevant microscopic processes in the proteome are complex formation and dissociation, and the microscopic degrees of freedom are the evolving concentrations of unbound proteins (in multiple post-translational states) and of protein complexes. Here we only include dimer-complexes, for mathematical simplicity, and we draw the network that describes which proteins are reaction partners from an ensemble of random graphs with an arbitrary degree distribution. We show how generating functional analysis methods can be used successfully to derive closed equations for dynamical order parameters, representing an exact macroscopic description of the complex formation and dissociation dynamics in the infinite system limit. We end this paper with a discussion of the possible routes towards solving the nontrivial order parameter equations, either exactly (in specific limits) or approximately.

  15. Alliance group formation: enabling and constraining effects of embeddedness and social capital in strategic technology alliance networks

    NARCIS (Netherlands)

    Duysters, G.M.; Lemmens, C.E.A.V.

    2003-01-01

    The role of embeddedness and social capital in the process of alliance group formation in strategic technology alliance networks is examined. In particular, the social mechanisms that enable and enforce alliance group formation is studies. It is argued that the enabling effect of embeddedness during

  16. Social media in vascular surgery.

    Science.gov (United States)

    Indes, Jeffrey E; Gates, Lindsay; Mitchell, Erica L; Muhs, Bart E

    2013-04-01

    There has been a tremendous growth in the use of social media to expand the visibility of various specialties in medicine. The purpose of this paper is to describe the latest updates on some current applications of social media in the practice of vascular surgery as well as existing limitations of use. This investigation demonstrates that the use of social networking sites appears to have a positive impact on vascular practice, as is evident through the incorporation of this technology at the Cleveland Clinic and by the Society for Vascular Surgery into their approach to patient care and physician communication. Overall, integration of social networking technology has current and future potential to be used to promote goals, patient awareness, recruitment for clinical trials, and professionalism within the specialty of vascular surgery. Copyright © 2013 Society for Vascular Surgery. Published by Mosby, Inc. All rights reserved.

  17. Visualization and Analysis of a Cardio Vascular Diseaseand MUPP1-related Biological Network combining Text Mining and Data Warehouse Approaches

    Directory of Open Access Journals (Sweden)

    Sommer Björn

    2010-03-01

    Full Text Available Detailed investigation of socially important diseases with modern experimental methods has resulted in the generation of large volume of valuable data. However, analysis and interpretation of this data needs application of efficient computational techniques and systems biology approaches. In particular, the techniques allowing the reconstruction of associative networks of various biological objects and events can be useful. In this publication, the combination of different techniques to create such a network associated with an abstract cell environment is discussed in order to gain insights into the functional as well as spatial interrelationships. It is shown that experimentally gained knowledge enriched with data warehouse content and text mining data can be used for the reconstruction and localization of a cardiovascular disease developing network beginning with MUPP1/MPDZ (multi-PDZ domain protein.

  18. Deep multi-scale location-aware 3D convolutional neural networks for automated detection of lacunes of presumed vascular origin.

    Science.gov (United States)

    Ghafoorian, Mohsen; Karssemeijer, Nico; Heskes, Tom; Bergkamp, Mayra; Wissink, Joost; Obels, Jiri; Keizer, Karlijn; de Leeuw, Frank-Erik; Ginneken, Bram van; Marchiori, Elena; Platel, Bram

    2017-01-01

    Lacunes of presumed vascular origin (lacunes) are associated with an increased risk of stroke, gait impairment, and dementia and are a primary imaging feature of the small vessel disease. Quantification of lacunes may be of great importance to elucidate the mechanisms behind neuro-degenerative disorders and is recommended as part of study standards for small vessel disease research. However, due to the different appearance of lacunes in various brain regions and the existence of other similar-looking structures, such as perivascular spaces, manual annotation is a difficult, elaborative and subjective task, which can potentially be greatly improved by reliable and consistent computer-aided detection (CAD) routines. In this paper, we propose an automated two-stage method using deep convolutional neural networks (CNN). We show that this method has good performance and can considerably benefit readers. We first use a fully convolutional neural network to detect initial candidates. In the second step, we employ a 3D CNN as a false positive reduction tool. As the location information is important to the analysis of candidate structures, we further equip the network with contextual information using multi-scale analysis and integration of explicit location features. We trained, validated and tested our networks on a large dataset of 1075 cases obtained from two different studies. Subsequently, we conducted an observer study with four trained observers and compared our method with them using a free-response operating characteristic analysis. Shown on a test set of 111 cases, the resulting CAD system exhibits performance similar to the trained human observers and achieves a sensitivity of 0.974 with 0.13 false positives per slice. A feasibility study also showed that a trained human observer would considerably benefit once aided by the CAD system.

  19. Defects formation and spiral waves in a network of neurons in presence of electromagnetic induction.

    Science.gov (United States)

    Rostami, Zahra; Jafari, Sajad

    2018-04-01

    Complex anatomical and physiological structure of an excitable tissue (e.g., cardiac tissue) in the body can represent different electrical activities through normal or abnormal behavior. Abnormalities of the excitable tissue coming from different biological reasons can lead to formation of some defects. Such defects can cause some successive waves that may end up to some additional reorganizing beating behaviors like spiral waves or target waves. In this study, formation of defects and the resulting emitted waves in an excitable tissue are investigated. We have considered a square array network of neurons with nearest-neighbor connections to describe the excitable tissue. Fundamentally, electrophysiological properties of ion currents in the body are responsible for exhibition of electrical spatiotemporal patterns. More precisely, fluctuation of accumulated ions inside and outside of cell causes variable electrical and magnetic field. Considering undeniable mutual effects of electrical field and magnetic field, we have proposed the new Hindmarsh-Rose (HR) neuronal model for the local dynamics of each individual neuron in the network. In this new neuronal model, the influence of magnetic flow on membrane potential is defined. This improved model holds more bifurcation parameters. Moreover, the dynamical behavior of the tissue is investigated in different states of quiescent, spiking, bursting and even chaotic state. The resulting spatiotemporal patterns are represented and the time series of some sampled neurons are displayed, as well.

  20. MiR-29b Downregulation Induces Phenotypic Modulation of Vascular Smooth Muscle Cells: Implication for Intracranial Aneurysm Formation and Progression to Rupture

    Directory of Open Access Journals (Sweden)

    Liqian Sun

    2017-01-01

    Full Text Available Background/Aims: Our previous microarray results identified numerous microRNAs (miRNAs, including miR-29b, that were differentially expressed in the serum of intracranial aneurysm (IA patients. The current study aimed to investigate whether miR-29b downregulation in IA could promote the phenotypic modulation of vascular smooth muscle cells (VSMCs involved in the pathogenesis of aneurysm by activating ATG14-mediated autophagy. Methods: First, the levels of miR-29b and autophagy related genes (ATGs between IA patients and normal subjects were compared. Next, we modified the level of miR-29b via lentivirus particles in the VSMCs and examined the effects of miR-29b on proliferation, migration, and phenotypic modulation of VSMCs from a contractile phenotype to a synthetic phenotype, as well as the levels of autophagy. Finally, the binding of miR-29b to the 3’UTR of ATG14 mRNA and its effects on ATG14 expression were analysed by a luciferase reporter assay and Western blot, respectively. Results: The level of miR-29b was decreased, and autophagy markers were increased in the IA patients compared to that of the normal subjects. Knockdown of miR-29b significantly promoted VSMCs proliferation and migration and, more importantly, induced the phenotypic modulation associated with autophagy activation, whereas miR-29b overexpression showed the opposite effects. The luciferase reporter assay demonstrated that ATG14 was a functional target gene of miR-29b. Notably, knockdown of ATG14 by siRNA apparently abrogated miR-29b inhibition-mediated phenotypic modulation. Conclusion: Downregulation of miR-29b induced VSMCs phenotypic modulation by directly activating ATG14-mediated autophagy, which is associated with the formation, growth and rupture of IAs.

  1. MiR-29b Downregulation Induces Phenotypic Modulation of Vascular Smooth Muscle Cells: Implication for Intracranial Aneurysm Formation and Progression to Rupture.

    Science.gov (United States)

    Sun, Liqian; Zhao, Manman; Zhang, Jingbo; Lv, Ming; Li, Youxiang; Yang, Xinjian; Liu, Aihua; Wu, Zhongxue

    2017-01-01

    Our previous microarray results identified numerous microRNAs (miRNAs), including miR-29b, that were differentially expressed in the serum of intracranial aneurysm (IA) patients. The current study aimed to investigate whether miR-29b downregulation in IA could promote the phenotypic modulation of vascular smooth muscle cells (VSMCs) involved in the pathogenesis of aneurysm by activating ATG14-mediated autophagy. First, the levels of miR-29b and autophagy related genes (ATGs) between IA patients and normal subjects were compared. Next, we modified the level of miR-29b via lentivirus particles in the VSMCs and examined the effects of miR-29b on proliferation, migration, and phenotypic modulation of VSMCs from a contractile phenotype to a synthetic phenotype, as well as the levels of autophagy. Finally, the binding of miR-29b to the 3'UTR of ATG14 mRNA and its effects on ATG14 expression were analysed by a luciferase reporter assay and Western blot, respectively. The level of miR-29b was decreased, and autophagy markers were increased in the IA patients compared to that of the normal subjects. Knockdown of miR-29b significantly promoted VSMCs proliferation and migration and, more importantly, induced the phenotypic modulation associated with autophagy activation, whereas miR-29b overexpression showed the opposite effects. The luciferase reporter assay demonstrated that ATG14 was a functional target gene of miR-29b. Notably, knockdown of ATG14 by siRNA apparently abrogated miR-29b inhibition-mediated phenotypic modulation. Downregulation of miR-29b induced VSMCs phenotypic modulation by directly activating ATG14-mediated autophagy, which is associated with the formation, growth and rupture of IAs. © 2017 The Author(s) Published by S. Karger AG, Basel.

  2. Novel graphical approach as fouling pinch for increasing fouling formation period in heat exchanger network (HEN) state of the art

    International Nuclear Information System (INIS)

    Azad, Abazar Vahdat; Ghaebi, Hadi; Amidpour, Majid

    2011-01-01

    In this paper a new graphical tool is proposed for investigation of fouling formation period in heat exchanger networks (HEN). The objective of this paper is increasing the time that HEN can perform its desirable heat transfer operation without required cleaning process. In a typical heat exchanger network, fouling formation rate of some streams is more than other ones. The method obtained in this work is based on given more opportunity for fouling formation for streams with high fouling formation rate. In fact high fouling formation rate streams are replaced with low fouling formation rate streams between different heat exchangers so that more fouling formation opportunity may be given for HEN. Therefore the HEN cleaning time decreases in fixed time period and the high fouling formation streams should pass from the path that the low fouling formation rate stream previously has passed, and inversely. As a result, secondly stream with high fouling formation rate mixes with residues of primary stream (low fouling formation rate stream). Therefore we should consider to adoption and conformability of streams structures (for prevention of streams destruction) and thermal considerations (for desirable heat transfer). Outlet temperatures of hot and cold streams should state in predefined temperatures. For satisfying thermal consideration after streams replacement this approach can be used in plants that cleanliness and its operational costs are most important problem.

  3. Brains striving for coherence: Long-term cumulative plot formation in the default mode network.

    Science.gov (United States)

    Tylén, K; Christensen, P; Roepstorff, A; Lund, T; Østergaard, S; Donald, M

    2015-11-01

    Many everyday activities, such as engaging in conversation or listening to a story, require us to sustain attention over a prolonged period of time while integrating and synthesizing complex episodic content into a coherent mental model. Humans are remarkably capable of navigating and keeping track of all the parallel social activities of everyday life even when confronted with interruptions or changes in the environment. However, the underlying cognitive and neurocognitive mechanisms of such long-term integration and profiling of information remain a challenge to neuroscience. While brain activity is generally traceable within the short time frame of working memory (milliseconds to seconds), these integrative processes last for minutes, hours or even days. Here we report two experiments on story comprehension. Experiment I establishes a cognitive dissociation between our comprehension of plot and incidental facts in narratives: when episodic material allows for long-term integration in a coherent plot, we recall fewer factual details. However, when plot formation is challenged, we pay more attention to incidental facts. Experiment II investigates the neural underpinnings of plot formation. Results suggest a central role for the brain's default mode network related to comprehension of coherent narratives while incoherent episodes rather activate the frontoparietal control network. Moreover, an analysis of cortical activity as a function of the cumulative integration of narrative material into a coherent story reveals to linear modulations of right hemisphere posterior temporal and parietal regions. Together these findings point to key neural mechanisms involved in the fundamental human capacity for cumulative plot formation. Copyright © 2015 Elsevier Inc. All rights reserved.

  4. Formation of nano-hydroxyapatite crystal in situ in chitosan-pectin polyelectrolyte complex network

    Energy Technology Data Exchange (ETDEWEB)

    Li Junjie [Department of Polymer Science and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Research Institute of Polymeric Materials, Tianjin University, Tianjin, 300072 (China); Zhu Dunwan [Institute of Biomedical Engineering, Chinese Academy of Medical Sciences and Peking Union Medical College, Tianjin, 300072 (China); Yin Jianwei; Liu Yuxi [Department of Polymer Science and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Yao Fanglian, E-mail: yaofanglian@tju.edu.cn [Department of Polymer Science and Key Laboratory of Systems Bioengineering of Ministry of Education, School of Chemical Engineering and Technology, Tianjin University, Tianjin, 300072 (China); Yao Kangde [Research Institute of Polymeric Materials, Tianjin University, Tianjin, 300072 (China)

    2010-07-20

    Hydroxyapatite (HA)/polysaccharide composites have been widely used in bone tissue engineering due to their chemical similarity to natural bone. Polymer matrix-mediated synthesis of nano-hydroxyapatite is one of the simplest models for biomimetic. In this article, the nano-hydroxyapatite/chitosan-pectin (nHCP) composites were prepared through in situ mineralization of hydroxyapatite in chitosan-pectin polyelectrolyte complex (PEC) network. The formation processes of nHCP were investigated by X-ray diffraction (XRD) analysis. The interactions between nHA crystal and chitosan-pectin PEC networks were studied using Fourier Transform Infrared Spectroscopy (FTIR) and Differential Scanning Calorimetry (DSC). The morphology and structure of nHA crystal were characterized by XRD and Transmission Electron Microscope (TEM). Results suggested that the interfacial interactions between nano-hydroxyapatite crystal and chitosan-pectin PEC network assist the site specific nucleation and growth of nHA nanoparticles. The nHA crystals grow along the c-axis. In this process, pH value is the main factor to control the nucleation and growth of nHA crystal in chitosan-pectin PEC networks, because both the interactions' strength between nHA crystal and chitosan-pectin and diffusion rate of inorganic ions depend on the pH value of the reaction system. Apart from the pH value, the chitosan/pectin ratio and [Ca{sup 2+}] also take important effects on the formation of nHA crystal. An effective way to control the size of nHA crystal is to adjust the content of pectin and [Ca{sup 2+}]. It is interesting that the Zeta potential of nHCP composites is about - 30 mV when the chitosan/pectin ratio {<=} 1:1, and the dispersion solution of nHCP composites has higher stability, which provides the possibility to prepare 3D porous scaffolds with nHCP for bone tissue engineering.

  5. Macrophage conditioned medium induced cellular network formation in MCF-7 cells through enhanced tunneling nanotube formation and tunneling nanotube mediated release of viable cytoplasmic fragments.

    Science.gov (United States)

    Patheja, Pooja; Sahu, Khageswar

    2017-06-15

    Infiltrating macrophages in tumor microenvironment, through their secreted cytokines and growth factors, regulate several processes of cancer progression such as cancer cell survival, proliferation, invasion, metastasis and angiogenesis. Recently, intercellular cytoplasmic bridges between cancer cells referred as tunneling nanotubes (TNTs) have been recognized as novel mode of intercellular communication between cancer cells. In this study, we investigated the effect of inflammatory mediators present in conditioned medium derived from macrophages on the formation of TNTs in breast adenocarcinoma cells MCF-7. Results show that treatment with macrophage conditioned medium (MɸCM) not only enhanced TNT formation between cells but also stimulated the release of independently migrating viable cytoplasmic fragments, referred to as microplasts, from MCF-7 cells. Time lapse microscopy revealed that microplasts were released from parent cancer cells in extracellular space through formation of TNT-like structures. Mitochondria, vesicles and cytoplasm could be transferred from parent cell body to microplasts through connecting TNTs. The microplasts could also be resorbed into the parent cell body by retraction of the connecting TNTs. Microplast formation inhibited in presence cell migration inhibitor, cytochalasin-B. Notably by utilizing migratory machinery within microplasts, distantly located MCF-7 cells formed several TNT based intercellular connections, leading to formation of physically connected network of cells. Together, these results demonstrate novel role of TNTs in microplast formation, novel modes of TNT formation mediated by microplasts and stimulatory effect of MɸCM on cellular network formation in MCF-7 cells mediated through enhanced TNT and microplast formation. Copyright © 2017 Elsevier Inc. All rights reserved.

  6. Molecular biology of breast cancer metastasis Molecular expression of vascular markers by aggressive breast cancer cells

    International Nuclear Information System (INIS)

    Hendrix, Mary JC; Seftor, Elisabeth A; Kirschmann, Dawn A; Seftor, Richard EB

    2000-01-01

    During embryogenesis, the formation of primary vascular networks occurs via the processes of vasculogenesis and angiogenesis. In uveal melanoma, vasculogenic mimicry describes the 'embryonic-like' ability of aggressive, but not nonaggressive, tumor cells to form networks surrounding spheroids of tumor cells in three-dimensional culture; these recapitulate the patterned networks seen in patients' aggressive tumors and correlates with poor prognosis. The molecular profile of these aggressive tumor cells suggests that they have a deregulated genotype, capable of expressing vascular phenotypes. Similarly, the embryonic-like phenotype expressed by the aggressive human breast cancer cells is associated with their ability to express a variety of vascular markers. These studies may offer new insights for consideration in breast cancer diagnosis and therapeutic intervention strategies

  7. [The long journey of Milton Santos's exile and the formation of his network of cooperation].

    Science.gov (United States)

    Pedrosa, Breno Viotto

    2018-01-01

    Based on an analysis of letters from the Milton Santos collection, the article revisits his journey through exile and shows how he contributed to solidifying the field of critical geography. It also pinpoints elements that reveal the genesis of his intellectual network, which involved thinkers from France, the United States, and Latin America. Focusing on the contexts of his exile, the article links his experiences outside Brazil to new scientific interests and the formation of an international circle of cooperation. Secondarily, it provides evidence of his concern with planning. It is found that his interest in the group of Pierre George and François Perroux was followed by a critical stance that moved him toward dialogue with Marxist philosophy and structuralism.

  8. Neural network-based distributed attitude coordination control for spacecraft formation flying with input saturation.

    Science.gov (United States)

    Zou, An-Min; Kumar, Krishna Dev

    2012-07-01

    This brief considers the attitude coordination control problem for spacecraft formation flying when only a subset of the group members has access to the common reference attitude. A quaternion-based distributed attitude coordination control scheme is proposed with consideration of the input saturation and with the aid of the sliding-mode observer, separation principle theorem, Chebyshev neural networks, smooth projection algorithm, and robust control technique. Using graph theory and a Lyapunov-based approach, it is shown that the distributed controller can guarantee the attitude of all spacecraft to converge to a common time-varying reference attitude when the reference attitude is available only to a portion of the group of spacecraft. Numerical simulations are presented to demonstrate the performance of the proposed distributed controller.

  9. Simultaneous wavelength and format conversion in SDN/NFV for flexible optical network based on FWM in SOA

    Science.gov (United States)

    Zhan, Yueying; Wang, Danshi; Zhang, Min

    2018-04-01

    We propose an all-optical wavelength and format conversion model (CM) for a dynamic data center interconnect node and coherent passive optical network (PON) optical network unit (ONU) in software-defined networking and network function virtualization system based on four-wave mixing in a semiconductor optical amplifier. Five wavelength converted DQPSK signals and two format converted DPSK signals are generated; the performances of the generated signals for two strategies of setting CM in the data center interconnect node and coherent PON ONU, which are over 10 km fiber transmission, have been verified. All of the converted signals are with a power penalty less than 2.2 dB at FEC threshold of 3.8 × 10 - 3, and the optimum bias current of SOA is 300 mA.

  10. The Drayang Girls of Thimphu: sexual network formation, transactional sex and emerging modernities in Bhutan.

    Science.gov (United States)

    Lorway, Robert; Dorji, Gampo; Bradley, Janet; Ramesh, B M; Isaac, Shajy; Blanchard, James

    2011-12-01

    Bhutan's sustained low HIV prevalence can be attributed to its political commitment to maintain isolation from foreign cultural influence. Recently, rising HIV prevalence has coincided with the increase in human traffic along Bhutan's borders. The majority of infections, occurring primarily through sexual contact, have appeared in the urban environments that are situated along the main transport routes. This qualitative study explored the sexual networks that form at entertainment venues in the capital city of Thimphu. To more fully understand sexual network formation at theses venues, one must take into account an emerging modernity that reflects a convergence of cultural, economic and political influences emanating from Bhutan's unique 'middle-path' modernisation scheme. The growing appearance of transactional sex in Thimphu not only points to an emergent form of exploitation wrought by larger economic transformations and widening social inequalities; the power inequalities that surround its practice are also significantly exacerbated by the local cultural politics and moral ideologies that arise as Bhutan proceeds along the path towards global capitalism. Discourses of Bhutanese sexual morality articulate with broader political economic transformations to forcefully position village women engaging in transactional sex within a field of power relations that leaves them open to various forms of subjugation.

  11. Industrie 4.0: Network Formation on a Distributed Manufacturing Project

    Directory of Open Access Journals (Sweden)

    Luiz Fernando Cardoso dos Santos Durão

    2017-09-01

    Full Text Available The integration of modern internet technology and manufacturing technology, which has been denominated Industrie 4.0, allows for distributed manufacturing using additive manufacturing on a global scale with the integration of machines and processes. However, distributed manufacturing poses many challenges for standardization, quality control and management of information in different manufacturing sites. This article aims to investigate the formation of networks in distributed manufacturing projects, identifying the stake-holders and types of connections throughout the project. The methodological approach used was longitudinal action research for a distributed manufacturing project with a focus on flexible manufacturing. The central plant was located in Germany and the supplier located in Brazil, with a partnership between the Polytechnic School of the University of São Paulo and the Technical University of Darmstadt, Germany. The design and engineering that spawned the product model was developed in Germany, while the additive manufacturing site, the structure, and machinery was developed in Brazil, forming a development and distributed manufacturing network. The results showed how organized the communication and knowledge sharing was among those involved in the distributed manufacturing project, as well as an understanding of what kind of knowledge is shared among those involved.

  12. Students Mental Representation of Biology Diagrams/Pictures Conventions Based on Formation of Causal Network

    Science.gov (United States)

    Sampurno, A. W.; Rahmat, A.; Diana, S.

    2017-09-01

    Diagrams/pictures conventions is one form of visual media that often used to assist students in understanding the biological concepts. The effectiveness of use diagrams/pictures in biology learning at school level has also been mostly reported. This study examines the ability of high school students in reading diagrams/pictures biological convention which is described by Mental Representation based on formation of causal networks. The study involved 30 students 11th grade MIA senior high school Banten Indonesia who are studying the excretory system. MR data obtained by Instrument worksheet, developed based on CNET-protocol, in which there are diagrams/drawings of nephron structure and urinary mechanism. Three patterns formed MR, namely Markov chain, feedback control with a single measurement, and repeated feedback control with multiple measurement. The third pattern is the most dominating pattern, differences in the pattern of MR reveal the difference in how and from which point the students begin to uncover important information contained in the diagram to establish a causal networks. Further analysis shows that a difference in the pattern of MR relate to how complex the students process the information contained in the diagrams/pictures.

  13. Prediction of hydrate formation temperature by both statistical models and artificial neural network approaches

    International Nuclear Information System (INIS)

    Zahedi, Gholamreza; Karami, Zohre; Yaghoobi, Hamed

    2009-01-01

    In this study, various estimation methods have been reviewed for hydrate formation temperature (HFT) and two procedures have been presented. In the first method, two general correlations have been proposed for HFT. One of the correlations has 11 parameters, and the second one has 18 parameters. In order to obtain constants in proposed equations, 203 experimental data points have been collected from literatures. The Engineering Equation Solver (EES) and Statistical Package for the Social Sciences (SPSS) soft wares have been employed for statistical analysis of the data. Accuracy of the obtained correlations also has been declared by comparison with experimental data and some recent common used correlations. In the second method, HFT is estimated by artificial neural network (ANN) approach. In this case, various architectures have been checked using 70% of experimental data for training of ANN. Among the various architectures multi layer perceptron (MLP) network with trainlm training algorithm was found as the best architecture. Comparing the obtained ANN model results with 30% of unseen data confirms ANN excellent estimation performance. It was found that ANN is more accurate than traditional methods and even our two proposed correlations for HFT estimation.

  14. Performance evaluation of multilevel modulation formats using partial response for capacity upgrade in access network with limited electronic bandwidth

    DEFF Research Database (Denmark)

    Madsen, Peter; Suhr, Lau Frejstrup; Rodríguez Páez, Juan Sebastián

    2016-01-01

    We present a successful experimental evaluation of 4 level Pulse Amplitude Modulation (4-PAM) and Duobinary modulation. An experimental performance evaluation is presented for Duobinary 4 PAM and other modulation formats. All modulation formants used, may be considered to be implemented in future...... Passive Optical Network (PON) class access networks with limited electrical bandwidth. We compared NRZ, Duobinary, 4-PAM and Duobinary 4-PAM operating at 9 Gbaud over 20 km single mode fiber. The results provides an insight and guidelines on the utilization of these advanced modulation formats....

  15. Hyperglycemia-Induced Modulation of the Physiognomy and Angiogenic Potential of Fibroblasts Mediated by Matrix Metalloproteinase-2: Implications for Venous Stenosis Formation Associated with Hemodialysis Vascular Access in Diabetic Milieu.

    Science.gov (United States)

    Janardhanan, Rajiv; Kilari, Sreenivasulu; Leof, Edward B; Misra, Sanjay

    2015-01-01

    It is hypothesized that venous stenosis formation associated with hemodialysis vascular-access failure is caused by hypoxia-mediated fibroblast-to-myofibroblast differentiation accompanied by proliferation and migration, and that diabetic patients have worse clinical outcomes. The aim of this study was to determine the functional and gene expression outcomes of matrix metalloproteinase-2 (Mmp-2) silencing in fibroblasts cultured under hyperglycemia and euglycemia with hypoxic and normoxic stimuli. AKR-2B fibroblasts were stably transduced using lentivirus-mediated shRNA-Mmp-2 or scrambled controls and subjected to hypoxia or normoxia under hyperglycemic or euglycemic conditions for 24 and 72 h. Gene expression of vascular endothelial growth factor-A (Vegf-A), Vegfr-1, Mmp-2, Mmp-9 and tissue inhibitors of matrix metalloproteinases (Timps) were determined by RT-PCR. Collagen I and IV secretion and cellular proliferation and migration were determined. Under hyperglycemic conditions, there is a significant reduction in the average gene expression of Vegf-A and Mmp-9, with an increase in Timp-1 at 24 h of hypoxia (p < 0.05) in Mmp-2-silenced fibroblasts when compared to controls. In addition, there is a decrease in collagen I and IV secretion and cellular migration. The euglycemic cells were able to reverse these findings. These findings demonstrate the rationale for using anti-Mmp-2 therapy in dialysis patients with hemodialysis vascular access in helping to reduce stenosis formation. © 2016 The Author(s) Published by S. Karger AG, Basel.

  16. Gas bubble network formation in irradiated beryllium pebbles monitored by X-Ray micro-tomography

    Energy Technology Data Exchange (ETDEWEB)

    Bolier, E; Ferrero, C. [Forschungszentrum Karlsruhe, Zimer 203, Gebaeude 451, Abteilung HVT-TL (Germany); Moslang, A. [Forschungszentrum Karlsruhe GmbH, FZK, Karlsruhe (Germany); Pieritz, R.A. [CNRS, Lab. de Glaciologie et Geophysique de l' Environnement, 38 - Saint Martin d' Heres (France)

    2007-07-01

    Full text of publication follows: The efficient and safe operation of helium cooled ceramic breeder blankets requires among others an efficient tritium release during operation at blanket relevant temperatures. In the past out-of-pile thermal desorption studies on low temperature neutron irradiated beryllium have shown that tritium and helium release peaks occur together. This phenomenon can be interpreted in terms of growth and coalescence of helium bubbles and tritium that either is trapped inside the helium bubbles in form of T{sub 2} molecules or in their strain field. With increasing temperature the bubble density and size at grain interfaces increase together with the probability of interconnected porosities and channel formation to the outer surface, leading to simultaneous helium and tritium release peaks in TDS. For a reliable prediction of gas release up to end-of-life conditions at blanket relevant temperatures, knowledge of the dynamics of bubble growth and coalescence as well as the 3D distribution of bubble network formation is indispensable. Such data could also be used to experimentally validate any future model predictions of tritium and helium release rates. A high resolution computer aided micro-tomography (CMT) setup has been developed at the European Synchrotron Radiation Facility which allowed reconstructing 3-D images of beryllium pebbles without damaging them. By postprocessing the data a 3D rendering of inner surfaces and of interconnected channel networks can be obtained, thus allowing the identification of open porosities in neutron irradiated and tempered beryllium pebbles. In our case Beryllium pebbles of 2 mm diameter had been neutron irradiated in the 'Beryllium' experiment at 770 K with 1.24 x 10{sup 25} nxm{sup -2} resulting in 480 appm He and 12 appm Tritium. After annealing at 1500 K CMT was performed on the pebbles with 4.9 and 1.4 {mu}m voxel resolution, respectively, followed by morphological and topological post

  17. Applying of the Artificial Neural Networks (ANN) to Identify and Characterize Sweet Spots in Shale Gas Formations

    Science.gov (United States)

    Puskarczyk, Edyta

    2018-03-01

    The main goal of the study was to enhance and improve information about the Ordovician and Silurian gas-saturated shale formations. Author focused on: firstly, identification of the shale gas formations, especially the sweet spots horizons, secondly, classification and thirdly, the accurate characterization of divisional intervals. Data set comprised of standard well logs from the selected well. Shale formations are represented mainly by claystones, siltstones, and mudstones. The formations are also partially rich in organic matter. During the calculations, information about lithology of stratigraphy weren't taken into account. In the analysis, selforganizing neural network - Kohonen Algorithm (ANN) was used for sweet spots identification. Different networks and different software were tested and the best network was used for application and interpretation. As a results of Kohonen networks, groups corresponding to the gas-bearing intervals were found. The analysis showed diversification between gas-bearing formations and surrounding beds. It is also shown that internal diversification in sweet spots is present. Kohonen algorithm was also used for geological interpretation of well log data and electrofacies prediction. Reliable characteristic into groups shows that Ja Mb and Sa Fm which are usually treated as potential sweet spots only partially have good reservoir conditions. It is concluded that ANN appears to be useful and quick tool for preliminary classification of members and sweet spots identification.

  18. Segmentation of white matter hyperintensities using convolutional neural networks with global spatial information in routine clinical brain MRI with none or mild vascular pathology.

    Science.gov (United States)

    Rachmadi, Muhammad Febrian; Valdés-Hernández, Maria Del C; Agan, Maria Leonora Fatimah; Di Perri, Carol; Komura, Taku

    2018-06-01

    We propose an adaptation of a convolutional neural network (CNN) scheme proposed for segmenting brain lesions with considerable mass-effect, to segment white matter hyperintensities (WMH) characteristic of brains with none or mild vascular pathology in routine clinical brain magnetic resonance images (MRI). This is a rather difficult segmentation problem because of the small area (i.e., volume) of the WMH and their similarity to non-pathological brain tissue. We investigate the effectiveness of the 2D CNN scheme by comparing its performance against those obtained from another deep learning approach: Deep Boltzmann Machine (DBM), two conventional machine learning approaches: Support Vector Machine (SVM) and Random Forest (RF), and a public toolbox: Lesion Segmentation Tool (LST), all reported to be useful for segmenting WMH in MRI. We also introduce a way to incorporate spatial information in convolution level of CNN for WMH segmentation named global spatial information (GSI). Analysis of covariance corroborated known associations between WMH progression, as assessed by all methods evaluated, and demographic and clinical data. Deep learning algorithms outperform conventional machine learning algorithms by excluding MRI artefacts and pathologies that appear similar to WMH. Our proposed approach of incorporating GSI also successfully helped CNN to achieve better automatic WMH segmentation regardless of network's settings tested. The mean Dice Similarity Coefficient (DSC) values for LST-LGA, SVM, RF, DBM, CNN and CNN-GSI were 0.2963, 0.1194, 0.1633, 0.3264, 0.5359 and 5389 respectively. Crown Copyright © 2018. Published by Elsevier Ltd. All rights reserved.

  19. A Probabilistic Approach to Network Event Formation from Pre-Processed Waveform Data

    Science.gov (United States)

    Kohl, B. C.; Given, J.

    2017-12-01

    The current state of the art for seismic event detection still largely depends on signal detection at individual sensor stations, including picking accurate arrivals times and correctly identifying phases, and relying on fusion algorithms to associate individual signal detections to form event hypotheses. But increasing computational capability has enabled progress toward the objective of fully utilizing body-wave recordings in an integrated manner to detect events without the necessity of previously recorded ground truth events. In 2011-2012 Leidos (then SAIC) operated a seismic network to monitor activity associated with geothermal field operations in western Nevada. We developed a new association approach for detecting and quantifying events by probabilistically combining pre-processed waveform data to deal with noisy data and clutter at local distance ranges. The ProbDet algorithm maps continuous waveform data into continuous conditional probability traces using a source model (e.g. Brune earthquake or Mueller-Murphy explosion) to map frequency content and an attenuation model to map amplitudes. Event detection and classification is accomplished by combining the conditional probabilities from the entire network using a Bayesian formulation. This approach was successful in producing a high-Pd, low-Pfa automated bulletin for a local network and preliminary tests with regional and teleseismic data show that it has promise for global seismic and nuclear monitoring applications. The approach highlights several features that we believe are essential to achieving low-threshold automated event detection: Minimizes the utilization of individual seismic phase detections - in traditional techniques, errors in signal detection, timing, feature measurement and initial phase ID compound and propagate into errors in event formation, Has a formalized framework that utilizes information from non-detecting stations, Has a formalized framework that utilizes source information, in

  20. The effect of volume exclusion on the formation of DNA minicircle networks: implications to kinetoplast DNA

    International Nuclear Information System (INIS)

    Diao, Y; Hinson, K; Sun, Y; Arsuaga, J

    2015-01-01

    Kinetoplast DNA (kDNA) is the mitochondrial of DNA of disease causing organisms such as Trypanosoma Brucei (T. Brucei) and Trypanosoma Cruzi (T. Cruzi). In most organisms, KDNA is made of thousands of small circular DNA molecules that are highly condensed and topologically linked forming a gigantic planar network. In our previous work we have developed mathematical and computational models to test the confinement hypothesis, that is that the formation of kDNA minicircle networks is a product of the high DNA condensation achieved in the mitochondrion of these organisms. In these studies we studied three parameters that characterize the growth of the network topology upon confinement: the critical percolation density, the mean saturation density and the mean valence (i.e. the number of mini circles topologically linked to any chosen minicircle). Experimental results on insect-infecting organisms showed that the mean valence is equal to three, forming a structure similar to those found in medieval chain-mails. These same studies hypothesized that this value of the mean valence was driven by the DNA excluded volume. Here we extend our previous work on kDNA by characterizing the effects of DNA excluded volume on the three descriptive parameters. Using computer simulations of polymer swelling we found that (1) in agreement with previous studies the linking probability of two minicircles does not decrease linearly with the distance between the two minicircles, (2) the mean valence grows linearly with the density of minicircles and decreases with the thickness of the excluded volume, (3) the critical percolation and mean saturation densities grow linearly with the thickness of the excluded volume. Our results therefore suggest that the swelling of the DNA molecule, due to electrostatic interactions, has relatively mild implications on the overall topology of the network. Our results also validate our topological descriptors since they appear to reflect the changes in the

  1. The effect of volume exclusion on the formation of DNA minicircle networks: implications to kinetoplast DNA

    Science.gov (United States)

    Diao, Y.; Hinson, K.; Sun, Y.; Arsuaga, J.

    2015-10-01

    Kinetoplast DNA (kDNA) is the mitochondrial of DNA of disease causing organisms such as Trypanosoma Brucei (T. Brucei) and Trypanosoma Cruzi (T. Cruzi). In most organisms, KDNA is made of thousands of small circular DNA molecules that are highly condensed and topologically linked forming a gigantic planar network. In our previous work we have developed mathematical and computational models to test the confinement hypothesis, that is that the formation of kDNA minicircle networks is a product of the high DNA condensation achieved in the mitochondrion of these organisms. In these studies we studied three parameters that characterize the growth of the network topology upon confinement: the critical percolation density, the mean saturation density and the mean valence (i.e. the number of mini circles topologically linked to any chosen minicircle). Experimental results on insect-infecting organisms showed that the mean valence is equal to three, forming a structure similar to those found in medieval chain-mails. These same studies hypothesized that this value of the mean valence was driven by the DNA excluded volume. Here we extend our previous work on kDNA by characterizing the effects of DNA excluded volume on the three descriptive parameters. Using computer simulations of polymer swelling we found that (1) in agreement with previous studies the linking probability of two minicircles does not decrease linearly with the distance between the two minicircles, (2) the mean valence grows linearly with the density of minicircles and decreases with the thickness of the excluded volume, (3) the critical percolation and mean saturation densities grow linearly with the thickness of the excluded volume. Our results therefore suggest that the swelling of the DNA molecule, due to electrostatic interactions, has relatively mild implications on the overall topology of the network. Our results also validate our topological descriptors since they appear to reflect the changes in the

  2. VASCULAR SURGERY

    African Journals Online (AJOL)

    2016-06-02

    Jun 2, 2016 ... with the literature from South Africa over the last four decades, and reflects the high rate of interpersonal violence in the country.14,15 As expected, cervical ... via the intact circle of Willis in young patients is the most likely explanation for the lack of strokes. Five patients were referred to the Durban vascular ...

  3. Vascular Disorders

    Science.gov (United States)

    ... All Topics A-Z Videos Infographics Symptom Picker Anatomy Bones Joints Muscles Nerves Vessels Tendons About Hand Surgery What is a Hand Surgeon? What is a Hand Therapist? Media Find a Hand Surgeon Home Anatomy Vascular Disorders Email to a friend * required fields ...

  4. Formation of hybrid gold nanoparticle network aggregates by specific host-guest interactions in a turbulent flow reactor

    NARCIS (Netherlands)

    Weinhart-Mejia, R.; Huskens, Jurriaan

    2014-01-01

    A multi-inlet vortex mixer (MIVM) was used to investigate the formation of hybrid gold nanoparticle network aggregates under highly turbulent flow conditions. To form aggregates, gold nanoparticles were functionalized with β-cyclodextrin (CD) and mixed with adamantyl (Ad)-terminated

  5. Clastic polygonal networks around Lyot crater, Mars: Possible formation mechanisms from morphometric analysis

    Science.gov (United States)

    Brooker, L. M.; Balme, M. R.; Conway, S. J.; Hagermann, A.; Barrett, A. M.; Collins, G. S.; Soare, R. J.

    2018-03-01

    Polygonal networks of patterned ground are a common feature in cold-climate environments. They can form through the thermal contraction of ice-cemented sediment (i.e. formed from fractures), or the freezing and thawing of ground ice (i.e. formed by patterns of clasts, or ground deformation). The characteristics of these landforms provide information about environmental conditions. Analogous polygonal forms have been observed on Mars leading to inferences about environmental conditions. We have identified clastic polygonal features located around Lyot crater, Mars (50°N, 30°E). These polygons are unusually large (>100 m diameter) compared to terrestrial clastic polygons, and contain very large clasts, some of which are up to 15 metres in diameter. The polygons are distributed in a wide arc around the eastern side of Lyot crater, at a consistent distance from the crater rim. Using high-resolution imaging data, we digitised these features to extract morphological information. These data are compared to existing terrestrial and Martian polygon data to look for similarities and differences and to inform hypotheses concerning possible formation mechanisms. Our results show the clastic polygons do not have any morphometric features that indicate they are similar to terrestrial sorted, clastic polygons formed by freeze-thaw processes. They are too large, do not show the expected variation in form with slope, and have clasts that do not scale in size with polygon diameter. However, the clastic networks are similar in network morphology to thermal contraction cracks, and there is a potential direct Martian analogue in a sub-type of thermal contraction polygons located in Utopia Planitia. Based upon our observations, we reject the hypothesis that polygons located around Lyot formed as freeze-thaw polygons and instead an alternative mechanism is put forward: they result from the infilling of earlier thermal contraction cracks by wind-blown material, which then became

  6. Sida rhomboidea.Roxb aqueous extract down-regulates in vivo expression of vascular cell adhesion molecules in atherogenic rats and inhibits in vitro macrophage differentiation and foam cell formation.

    Science.gov (United States)

    Thounaojam, Menaka C; Jadeja, Ravirajsinh N; Salunke, Sunita P; Devkar, Ranjitsinh V; Ramachandran, A V

    2012-10-01

    The present study evaluates efficacy of Sida rhomboidea.Roxb (SR) leaves extract in ameliorating experimental atherosclerosis using in vitro and in vivo experimental models. Atherogenic (ATH) diet fed rats recorded significant increment in the serum total cholesterol (TC), triglycerides (TG), low-density lipoprotein (LDL), very LDL (VLDL), autoantibody against oxidized LDL (Ox-LDL), markers of LDL oxidation and decrement in high-density lipoprotein (HDL) along with increment in aortic TC and TG. The ex vivo LDL oxidation assay revealed an increased susceptibility of LDL isolated from ATH rats to undergo copper mediated oxidation. These set of changes were minimized by simultaneous co-supplementation of SR extract to ATH diet fed rats. Histopathology of aorta and immunolocalization studies recorded pronounced atheromatous plaque formation, vascular calcification, significant elastin derangements and higher expression of macrophage surface marker (F4/80), vascular cell adhesion molecule-1 (VCAM-1) and p-selectin in ATH rats. Whereas, ATH+SR rats depicted minimal evidence of atheromatous plaque formation, calcium deposition, distortion/defragmentation of elastin and accumulation of macrophages along with lowered expression of VCAM-1 and P-selectin compared to ATH rats. Further, monocyte to macrophage differentiation and in vitro foam cell formation were significantly attenuated in presence of SR extract. In conclusion, SR extract has the potency of controlling experimental atherosclerosis and can be used as promising herbal supplement in combating atherosclerosis.

  7. Modeling Networks and Dynamics in Complex Systems: from Nano-Composites to Opinion Formation

    Science.gov (United States)

    Shi, Feng

    Complex networks are ubiquitous in systems of physical, biological, social or technological origin. Components in those systems range from as large as cities in power grids, to as small as molecules in metabolic networks. Since the dawn of network science, significant attention has focused on the implications of dynamics in establishing network structure and the impact of structural properties on dynamics on those networks. The first part of the thesis follows this direction, studying the network formed by conductive nanorods in nano-materials, and focuses on the electrical response of the composite to the structure change of the network. New scaling laws for the shear-induced anisotropic percolation are introduced and a robust exponential tail of the current distribution across the network is identified. These results are relevant especially to "active" composite materials where materials are exposed to mechanical loading and strain deformations. However, in many real-world networks the evolution of the network topology is tied to the states of the vertices and vice versa. Networks that exhibit such a feedback are called adaptive or coevolutionary networks. The second part of the thesis examines two closely related variants of a simple, abstract model for coevolution of a network and the opinions of its members. As a representative model for adaptive networks, it displays the feature of self-organization of the system into a stable configuration due to the interplay between the network topology and the dynamics on the network. This simple model yields interesting dynamics and the slight change in the rewiring strategy results in qualitatively different behaviors of the system. In conclusion, the dissertation aims to develop new network models and tools which enable insights into the structure and dynamics of various systems, and seeks to advance network algorithms which provide approaches to coherently articulated questions in real-world complex systems such as

  8. Table-driven configuration and formatting of telemetry data in the Deep Space Network

    Science.gov (United States)

    Manning, Evan

    1994-01-01

    With a restructured software architecture for telemetry system control and data processing, the NASA/Deep Space Network (DSN) has substantially improved its ability to accommodate a wide variety of spacecraft in an era of 'better, faster, cheaper'. In the new architecture, the permanent software implements all capabilities needed by any system user, and text tables specify how these capabilities are to be used for each spacecraft. Most changes can now be made rapidly, outside of the traditional software development cycle. The system can be updated to support a new spacecraft through table changes rather than software changes, reducing the implementation, test, and delivery cycle for such a change from three months to three weeks. The mechanical separation of the text table files from the program software, with tables only loaded into memory when that mission is being supported, dramatically reduces the level of regression testing required. The format of each table is a different compromise between ease of human interpretation, efficiency of computer interpretation, and flexibility.

  9. Assembly of phosphide nanocrystals into porous networks: formation of InP gels and aerogels.

    Science.gov (United States)

    Hitihami-Mudiyanselage, Asha; Senevirathne, Keerthi; Brock, Stephanie L

    2013-02-26

    The applicability of sol-gel nanoparticle assembly routes, previously employed for metal chalcogenides, to phosphides is reported for the case of InP. Two different sizes (3.5 and 6.0 nm) of InP nanoparticles were synthesized by solution-phase arrested precipitation, capped with thiolate ligands, and oxidized with H₂O₂ or O₂/light to induce gel formation. The gels were aged, solvent-exchanged, and then supercritically dried to obtain aerogels with both meso- (2-50 nm) and macropores (>50 nm) and accessible surface areas of ∼200 m²/g. Aerogels showed higher band gap values relative to precursor nanoparticles, suggesting that during the process of assembling nanoparticles into 3D architectures, particle size reduction may have taken place. In contrast to metal chalcogenide gelation, InP gels did not form using tetranitromethane, a non-oxygen-transferring oxidant. The requirement of an oxygen-transferring oxidant, combined with X-ray photoelectron spectroscopy data showing oxidized phosphorus, suggests gelation is occurring due to condensation of phosphorus oxoanionic moieties generated at the interfaces. The ability to link discrete InP nanoparticles into a 3D porous network while maintaining quantum confinement is expected to facilitate exploitation of nanostructured InP in solid-state devices.

  10. Novel enzymatically cross-linked hyaluronan hydrogels support the formation of 3D neuronal networks.

    Science.gov (United States)

    Broguiere, Nicolas; Isenmann, Luca; Zenobi-Wong, Marcy

    2016-08-01

    Hyaluronan (HA) is an essential component of the central nervous system's extracellular matrix and its high molecular weight (MW) form has anti-inflammatory and anti-fibrotic properties relevant for regenerative medicine. Here, we introduce a new hydrogel based on high MW HA which is cross-linked using the transglutaminase (TG) activity of the activated blood coagulation factor XIII (FXIIIa). These HA-TG gels have significant advantages for neural tissue engineering compared to previous HA gels. Due to their chemical inertness in the absence of FXIIIa, the material can be stored long-term, is stable in solution, and shows no cytotoxicity. The gelation is completely cell-friendly due to the specificity of the enzyme and the gelation rate can be tuned from seconds to hours at physiological pH and independently of stiffness. The gels are injectable, and attach covalently to fibrinogen and fibrin, two common bioactive components in in vitro tissue engineering, as well as proteins present in vivo, allowing the gels to covalently bind to brain or spinal cord defects. These optimal chemical and bioactive properties of HA-TG gels enabled the formation of 3D neuronal cultures of unprecedented performance, showing fast neurite outgrowth, axonal and dendritic speciation, strong synaptic connectivity in 3D networks, and rapidly-occurring and long-lasting coordinated electrical activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

  11. Mechanism of Retinal Pigment Epithelium Tear Formation Following Intravitreal Anti–Vascular Endothelial Growth Factor Therapy Revealed by Spectral-Domain Optical Coherence Tomography

    DEFF Research Database (Denmark)

    Nagiel, Aaron; Freund, K Bailey; Spaide, Richard F

    2013-01-01

    to the retracted RPE. In all eyes, the RPE ruptured along a segment of bare RPE not in contact with the CNV or Bruch membrane. CONCLUSIONS: Eyes with vascularized PEDs secondary to AMD may show specific OCT findings that increase the risk for RPE tear following intravitreal anti-VEGF injection. Rapid involution......PURPOSE: To demonstrate the mechanism by which retinal pigment epithelium (RPE) tears occur in eyes with neovascular age-related macular degeneration (AMD) treated with intravitreal anti-vascular endothelial growth factor (VEGF) agents using spectral-domain optical coherence tomography (OCT......). DESIGN: Retrospective observational case series. METHODS: OCT images of 8 eyes that developed RPE tears following the administration of intravitreal anti-VEGF agents for neovascular AMD were evaluated. Pretear and posttear images were compared in order to elucidate the mechanism by which RPE tears occur...

  12. A pilot study to image the vascular network of small melanocytic choroidal tumors with speckle noise-free 1050-nm swept source optical coherence tomography (OCT choroidal angiography).

    Science.gov (United States)

    Maloca, Peter; Gyger, Cyrill; Hasler, Pascal W

    2016-06-01

    To visualize and measure the vascular network of melanocytic choroidal tumors with speckle noise-free swept source optical coherence tomography (SS-OCT choroidal angiography). Melanocytic choroidal tumors from 24 eyes were imaged with 1050-nm optical coherence tomography (Topcon DRI OCT-1 Atlantis). A semi-automated algorithm was developed to remove speckle noise and to extract and measure the volume of the choroidal vessels from the obtained OCT data. In all cases, analysis of the choroidal vessels could be performed with SS-OCT without the need for pupillary dilation. The proposed method allows speckle noise-free, structure-guided visualization and measurement of the larger choroidal vessels in three dimensions. The obtained data suggest that speckle noise-free OCT may be more effective at identifying choroidal structures than traditional OCT methods. The measured volume of the extracted choroidal vessels of Haller's layer and Sattler's layer in the examined tumorous eyes was on average 0.982463955 mm(3) /982463956 μm(3) (range of 0.209764406 mm(3) /209764405.9 μm(3)to 1.78105544 mm(3) /1781055440 μm(3)). Full thickness obstruction of the choroidal vasculature by the tumor was found in 18 cases (72 %). In seven cases (18 %), choroidal vessel architecture did not show pronounced morphological abnormalities (18 %). Speckle noise-free OCT may serve as a new illustrative imaging technology and enhance visualization of the choroidal vessels without the need for dye injection. OCT can be used to identify and evaluate the choroidal vessels of melanocytic choroidal tumors, and may represent a potentially useful tool for imaging and monitoring of choroidal nevi and melanoma.

  13. Network of vascular diseases, death and biochemical characteristics in a set of 4,197 patients with type 1 diabetes (The FinnDiane Study

    Directory of Open Access Journals (Sweden)

    Wadén Johan

    2009-10-01

    Full Text Available Background Cardiovascular disease is the main cause of premature death in patients with type 1 diabetes. Patients with diabetic kidney disease have an increased risk of heart attack or stroke. Accurate knowledge of the complex inter-dependencies between the risk factors is critical for pinpointing the best targets for research and treatment. Therefore, the aim of this study was to describe the association patterns between clinical and biochemical features of diabetic complications. Methods Medical records and serum and urine samples of 4,197 patients with type 1 diabetes were collected from health care centers in Finland. At baseline, the mean diabetes duration was 22 years, 52% were male, 23% had kidney disease (urine albumin excretion over 300 mg/24 h or end-stage renal disease and 8% had a history of macrovascular events. All-cause mortality was evaluated after an average of 6.5 years of follow-up (25,714 patient years. The dataset comprised 28 clinical and 25 biochemical variables that were regarded as the nodes of a network to assess their mutual relationships. Results The networks contained cliques that were densely inter-connected (r > 0.6, including cliques for high-density lipoprotein (HDL markers, for triglycerides and cholesterol, for urinary excretion and for indices of body mass. The links between the cliques showed biologically relevant interactions: an inverse relationship between HDL cholesterol and the triglyceride clique (r P -16, a connection between triglycerides and body mass via C-reactive protein (r > 0.3, P -16 and intermediate-density cholesterol as the connector between lipoprotein metabolism and albuminuria (r > 0.3, P -16. Aging and macrovascular disease were linked to death via working ability and retinopathy. Diabetic kidney disease, serum creatinine and potassium, retinopathy and blood pressure were inter-connected. Blood pressure correlations indicated accelerated vascular aging in individuals with kidney disease

  14. Distributed Adaptive Finite-Time Approach for Formation-Containment Control of Networked Nonlinear Systems Under Directed Topology.

    Science.gov (United States)

    Wang, Yujuan; Song, Yongduan; Ren, Wei

    2017-07-06

    This paper presents a distributed adaptive finite-time control solution to the formation-containment problem for multiple networked systems with uncertain nonlinear dynamics and directed communication constraints. By integrating the special topology feature of the new constructed symmetrical matrix, the technical difficulty in finite-time formation-containment control arising from the asymmetrical Laplacian matrix under single-way directed communication is circumvented. Based upon fractional power feedback of the local error, an adaptive distributed control scheme is established to drive the leaders into the prespecified formation configuration in finite time. Meanwhile, a distributed adaptive control scheme, independent of the unavailable inputs of the leaders, is designed to keep the followers within a bounded distance from the moving leaders and then to make the followers enter the convex hull shaped by the formation of the leaders in finite time. The effectiveness of the proposed control scheme is confirmed by the simulation.

  15. Vascular and micro-environmental influences on MSC-coral hydroxyapatite construct-based bone tissue engineering.

    Science.gov (United States)

    Cai, Lei; Wang, Qian; Gu, Congmin; Wu, Jingguo; Wang, Jian; Kang, Ning; Hu, Jiewei; Xie, Fang; Yan, Li; Liu, Xia; Cao, Yilin; Xiao, Ran

    2011-11-01

    Bone tissue engineering (BTE) has been demonstrated an effective approach to generate bone tissue and repair bone defect in ectopic and orthotopic sites. The strategy of using a prevascularized tissue-engineered bone grafts (TEBG) fabricated ectopically to repair bone defects, which is called live bone graft surgery, has not been reported. And the quantitative advantages of vascularization and osteogenic environment in promoting engineered bone formation have not been defined yet. In the current study we generated a tissue engineered bone flap with a vascular pedicle of saphenous arteriovenous in which an organized vascular network was observed after 4 weeks implantation, and followed by a successful repaire of fibular defect in beagle dogs. Besides, after a 9 months long term observation of engineered bone formation in ectopic and orthotopic sites, four CHA (coral hydroxyapatite) scaffold groups were evaluated by CT (computed tomography) analysis. By the comparison of bone formation and scaffold degradation between different groups, the influences of vascularization and micro-environment on tissue engineered bone were quantitatively analyzed. The results showed that in the first 3 months vascularization improved engineered bone formation by 2 times of non-vascular group and bone defect micro-environment improved it by 3 times of ectopic group, and the CHA-scaffold degradation was accelerated as well. Copyright © 2011 Elsevier Ltd. All rights reserved.

  16. Genetic Regulation of Vascular Development: Building the Zebrafish Vascular Tree

    NARCIS (Netherlands)

    R.L.J.M. Herpers (Robert)

    2010-01-01

    textabstractThe extensive networks of blood and lymphatic vessels within the vertebrate body are essential for the transport and delivery of fluids, gases, macromolecules and cells, and play important roles in facilitating immune responses. The development of the vascular tree requires a highly

  17. Vascular ultrasound.

    Science.gov (United States)

    Pilcher, D B; Ricci, M A

    1998-04-01

    Surgeon-interpreted diagnostic ultrasound has become the preferred screening test and often the definitive test for the diagnosis of arterial stenosis, aneurysm, and venous thrombosis. As a modality for surveillance, its noninvasive quality makes it particularly appealing as the test of choice to screen patients for abdominal aortic aneurysms or to perform follow-up examinations on those patients with a carotid endartectomy or in situ bypass grafts. The increasing reliance on intraoperative duplex imaging of vascular procedures demands that the surgeon learn the skills to perform the studies without a technologist or radiologist to interpret the examination.

  18. Taste masking of ofloxacin and formation of interpenetrating polymer network beads for sustained release

    Directory of Open Access Journals (Sweden)

    A. Michael Rajesh

    2017-08-01

    Full Text Available The objective of this study was to carry out taste masking of ofloxacin (Ofl by ion exchange resins (IERs followed by sustained release of Ofl by forming interpenetrating polymer network (IPN beads. Drug-resin complexes (DRCs with three different ratios of Ofl to IERs (1:1, 1:2, 1:4 were prepared by batch method and investigated for in vivo and in vitro taste masking. DRC of methacrylic acid-divinyl benzene (MD resin and Ofl prepared at a ratio of 1:4 was used to form IPN beads. IPN beads of MD 1:4 were prepared by following the ionic cross-linking method using sodium carboxymethyl xanthan gum (SCMXG and SCMXG-sodium carboxymethyl cellulose (SCMXG-SCMC. IPN beads were characterized with FT-IR and further studied on sustained release of Ofl at different pH. In vivo taste masking carried out by human volunteers showed that MD 1:4 significantly reduced the bitterness of Ofl. Characterization studies such as FT-IR, DSC, P-XRD and taste masking showed that complex formation took place between drug and resin. In vitro study at gastric pH showed complete release of drug from MD 1:4 within 30 min whereas IPN beads took 5 h at gastric pH and 10 h at salivary pH for the complete release of drug. As the crosslinking increased the release kinetics changed into non-Fickian diffusion to zero-order release mechanism. MD 1:4 showed better performance for the taste masking of Ofl and IPNs beads prepared from it were found useful for the sustained release of Ofl at both the pH, indicating a versatile drug delivery system.

  19. EEG in Silent Small Vessel Disease : sLORETA Mapping Reveals Cortical Sources of Vascular Cognitive Impairment No Dementia in the Default Mode Network

    NARCIS (Netherlands)

    Sheorajpanday, Rishi V. A.; Marien, Peter; Weeren, Arie J. T. M.; Nagels, Guy; Saerens, Jos; van Putten, Michel J. A. M.; De Deyn, Peter P.

    Introduction: Vascular cognitive impairment, no dementia (vCIND) is a prevalent and potentially preventable disorder. Clinical presof the small vessel subcortical subtype may be insidious and difficult to diagnose in the initial stage. We investigated electroencephalographic sources of subcortical

  20. A Low-Complexity Subgroup Formation with QoS-Aware for Enhancing Multicast Services in LTE Networks

    Science.gov (United States)

    Algharem, M.; Omar, M. H.; Rahmat, R. F.; Budiarto, R.

    2018-03-01

    The high demand of Multimedia services on in Long Term Evolution (LTE) and beyond networks forces the networks operators to find a solution that can handle the huge traffic. Along with this, subgroup formation techniques are introduced to overcome the limitations of the Conventional Multicast Scheme (CMS) by splitting the multicast users into several subgroups based on the users’ channels quality signal. However, finding the best subgroup configuration with low complexity is need more investigations. In this paper, an efficient and simple subgroup formation mechanisms are proposed. The proposed mechanisms take the transmitter MAC queue in account. The effectiveness of the proposed mechanisms is evaluated and compared with CMS in terms of throughput, fairness, delay, Block Error Rate (BLER).

  1. Mechanisms of Glioma Formation: Iterative Perivascular Glioma Growth and Invasion Leads to Tumor Progression, VEGF-Independent Vascularization, and Resistance to Antiangiogenic Therapy

    Directory of Open Access Journals (Sweden)

    Gregory J. Baker

    2014-07-01

    Full Text Available As glioma cells infiltrate the brain they become associated with various microanatomic brain structures such as blood vessels, white matter tracts, and brain parenchyma. How these distinct invasion patterns coordinate tumor growth and influence clinical outcomes remain poorly understood. We have investigated how perivascular growth affects glioma growth patterning and response to antiangiogenic therapy within the highly vascularized brain. Orthotopically implanted rodent and human glioma cells are shown to commonly invade and proliferate within brain perivascular space. This form of brain tumor growth and invasion is also shown to characterize de novo generated endogenous mouse brain tumors, biopsies of primary human glioblastoma (GBM, and peripheral cancer metastasis to the human brain. Perivascularly invading brain tumors become vascularized by normal brain microvessels as individual glioma cells use perivascular space as a conduit for tumor invasion. Agent-based computational modeling recapitulated biological perivascular glioma growth without the need for neoangiogenesis. We tested the requirement for neoangiogenesis in perivascular glioma by treating animals with angiogenesis inhibitors bevacizumab and DC101. These inhibitors induced the expected vessel normalization, yet failed to reduce tumor growth or improve survival of mice bearing orthotopic or endogenous gliomas while exacerbating brain tumor invasion. Our results provide compelling experimental evidence in support of the recently described failure of clinically used antiangiogenics to extend the overall survival of human GBM patients.

  2. Use of formative research and social network theory to develop a group walking intervention: Sumter County on the Move!

    Science.gov (United States)

    Forthofer, Melinda; Burroughs-Girardi, Ericka; Stoisor-Olsson, Liliana; Wilcox, Sara; Sharpe, Patricia A; Pekuri, Linda M

    2016-10-01

    Although social support is a frequently cited enabler of physical activity, few studies have examined how to harness social support in interventions. This paper describes community-based formative research to design a walking program for mobilizing naturally occurring social networks to support increases in walking behavior. Focus group methods were used to engage community members in discussions about desired walking program features. The research was conducted with underserved communities in Sumter County, South Carolina. The majority of focus group participants were women (76%) and African American (92%). Several important themes emerged from the focus group results regarding attitudes toward walking, facilitators of and barriers to walking, ideal walking program characteristics, and strategies for encouraging community members to walk. Most noteably, the role of existing social networks as a supportive influence on physical activity was a recurring theme in our formative research and a gap in the existing evidence base. The resulting walking program focused on strategies for mobilizing, supporting and reinforcing existing social networks as mechanisms for increasing walking. Our approach to linking theory, empirical evidence and community-based formative research for the development of a walking intervention offers an example for practitioners developing intervention strategies for a wide range of behaviors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  3. Formation of community-based hypertension practice networks: success, obstacles, and lessons learned.

    Science.gov (United States)

    Dart, Richard A; Egan, Brent M

    2014-06-01

    Community-based practice networks for research and improving the quality of care are growing in size and number but have variable success rates. In this paper, the authors review recent efforts to initiate a community-based hypertension network modeled after the successful Outpatient Quality Improvement Network (O'QUIN) project, located at the Medical University of South Carolina. Key lessons learned and new directions to be explored are highlighted. ©2014 Wiley Periodicals, Inc.

  4. Vascular malforma- tions part 1 — normal and abnormal vascular ...

    African Journals Online (AJOL)

    Enrique

    to form the primitive vascular plexus. Angiogenesis is the formation of new vessels by sprouting or splitting of ... The differentiation of primitive vessels into arteries, veins or capillaries is determined by flow patterns .... identify, but it is probable that as time progresses further specific genetic defects related to the development ...

  5. The Emergence of Embedded Relations and Group Formation in Networks of Competition

    Science.gov (United States)

    Thye, Shane R.; Lawler, Edward J.; Yoon, Jeongkoo

    2011-01-01

    This study examines how and when small networks of self-interested agents generate a group tie or affiliation at the network level. A group affiliation is formed when actors (a) perceive themselves as members of a group and (b) share resources with each other despite an underlying competitive structure. We apply a concept of structural cohesion to…

  6. A Team Formation and Project-based Learning Support Service for Social Learning Networks

    NARCIS (Netherlands)

    Spoelstra, Howard; Van Rosmalen, Peter; Van de Vrie, Evert; Obreza, Matija; Sloep, Peter

    2014-01-01

    The Internet affords new approaches to learning. Geographically dispersed self-directed learners can learn in computer-supported communities, forming social learning networks. However, self-directed learners can suffer from a lack of continuous motivation. And surprisingly, social learning networks

  7. The Aux/IAA gene rum1 involved in seminal and lateral root formation controls vascular patterning in maize (Zea mays L.) primary roots.

    Science.gov (United States)

    Zhang, Yanxiang; Paschold, Anja; Marcon, Caroline; Liu, Sanzhen; Tai, Huanhuan; Nestler, Josefine; Yeh, Cheng-Ting; Opitz, Nina; Lanz, Christa; Schnable, Patrick S; Hochholdinger, Frank

    2014-09-01

    The maize (Zea mays L.) Aux/IAA protein RUM1 (ROOTLESS WITH UNDETECTABLE MERISTEMS 1) controls seminal and lateral root initiation. To identify RUM1-dependent gene expression patterns, RNA-Seq of the differentiation zone of primary roots of rum1 mutants and the wild type was performed in four biological replicates. In total, 2 801 high-confidence maize genes displayed differential gene expression with Fc ≥2 and FDR ≤1%. The auxin signalling-related genes rum1, like-auxin1 (lax1), lax2, (nam ataf cuc 1 nac1), the plethora genes plt1 (plethora 1), bbm1 (baby boom 1), and hscf1 (heat shock complementing factor 1) and the auxin response factors arf8 and arf37 were down-regulated in the mutant rum1. All of these genes except nac1 were auxin-inducible. The maize arf8 and arf37 genes are orthologues of Arabidopsis MP/ARF5 (MONOPTEROS/ARF5), which controls the differentiation of vascular cells. Histological analyses of mutant rum1 roots revealed defects in xylem organization and the differentiation of pith cells around the xylem. Moreover, histochemical staining of enlarged pith cells surrounding late metaxylem elements demonstrated that their thickened cell walls displayed excessive lignin deposition. In line with this phenotype, rum1-dependent mis-expression of several lignin biosynthesis genes was observed. In summary, RNA-Seq of RUM1-dependent gene expression in maize primary roots, in combination with histological and histochemical analyses, revealed the specific regulation of auxin signal transduction components by RUM1 and novel functions of RUM1 in vascular development. © The Author 2014. Published by Oxford University Press on behalf of the Society for Experimental Biology.

  8. Vildagliptin Stimulates Endothelial Cell Network Formation and Ischemia-induced Revascularization via an Endothelial Nitric-oxide Synthase-dependent Mechanism*

    Science.gov (United States)

    Ishii, Masakazu; Shibata, Rei; Kondo, Kazuhisa; Kambara, Takahiro; Shimizu, Yuuki; Tanigawa, Tohru; Bando, Yasuko K.; Nishimura, Masahiro; Ouchi, Noriyuki; Murohara, Toyoaki

    2014-01-01

    Dipeptidyl peptidase-4 inhibitors are known to lower glucose levels and are also beneficial in the management of cardiovascular disease. Here, we investigated whether a dipeptidyl peptidase-4 inhibitor, vildagliptin, modulates endothelial cell network formation and revascularization processes in vitro and in vivo. Treatment with vildagliptin enhanced blood flow recovery and capillary density in the ischemic limbs of wild-type mice, with accompanying increases in phosphorylation of Akt and endothelial nitric-oxide synthase (eNOS). In contrast to wild-type mice, treatment with vildagliptin did not improve blood flow in ischemic muscles of eNOS-deficient mice. Treatment with vildagliptin increased the levels of glucagon-like peptide-1 (GLP-1) and adiponectin, which have protective effects on the vasculature. Both vildagliptin and GLP-1 increased the differentiation of cultured human umbilical vein endothelial cells (HUVECs) into vascular-like structures, although vildagliptin was less effective than GLP-1. GLP-1 and vildagliptin also stimulated the phosphorylation of Akt and eNOS in HUVECs. Pretreatment with a PI3 kinase or NOS inhibitor blocked the stimulatory effects of both vildagliptin and GLP-1 on HUVEC differentiation. Furthermore, treatment with vildagliptin only partially increased the limb flow of ischemic muscle in adiponectin-deficient mice in vivo. GLP-1, but not vildagliptin, significantly increased adiponectin expression in differentiated 3T3-L1 adipocytes in vitro. These data indicate that vildagliptin promotes endothelial cell function via eNOS signaling, an effect that may be mediated by both GLP-1-dependent and GLP-1-independent mechanisms. The beneficial activity of GLP-1 for revascularization may also be partially mediated by its ability to increase adiponectin production. PMID:25100725

  9. Vildagliptin stimulates endothelial cell network formation and ischemia-induced revascularization via an endothelial nitric-oxide synthase-dependent mechanism.

    Science.gov (United States)

    Ishii, Masakazu; Shibata, Rei; Kondo, Kazuhisa; Kambara, Takahiro; Shimizu, Yuuki; Tanigawa, Tohru; Bando, Yasuko K; Nishimura, Masahiro; Ouchi, Noriyuki; Murohara, Toyoaki

    2014-09-26

    Dipeptidyl peptidase-4 inhibitors are known to lower glucose levels and are also beneficial in the management of cardiovascular disease. Here, we investigated whether a dipeptidyl peptidase-4 inhibitor, vildagliptin, modulates endothelial cell network formation and revascularization processes in vitro and in vivo. Treatment with vildagliptin enhanced blood flow recovery and capillary density in the ischemic limbs of wild-type mice, with accompanying increases in phosphorylation of Akt and endothelial nitric-oxide synthase (eNOS). In contrast to wild-type mice, treatment with vildagliptin did not improve blood flow in ischemic muscles of eNOS-deficient mice. Treatment with vildagliptin increased the levels of glucagon-like peptide-1 (GLP-1) and adiponectin, which have protective effects on the vasculature. Both vildagliptin and GLP-1 increased the differentiation of cultured human umbilical vein endothelial cells (HUVECs) into vascular-like structures, although vildagliptin was less effective than GLP-1. GLP-1 and vildagliptin also stimulated the phosphorylation of Akt and eNOS in HUVECs. Pretreatment with a PI3 kinase or NOS inhibitor blocked the stimulatory effects of both vildagliptin and GLP-1 on HUVEC differentiation. Furthermore, treatment with vildagliptin only partially increased the limb flow of ischemic muscle in adiponectin-deficient mice in vivo. GLP-1, but not vildagliptin, significantly increased adiponectin expression in differentiated 3T3-L1 adipocytes in vitro. These data indicate that vildagliptin promotes endothelial cell function via eNOS signaling, an effect that may be mediated by both GLP-1-dependent and GLP-1-independent mechanisms. The beneficial activity of GLP-1 for revascularization may also be partially mediated by its ability to increase adiponectin production. © 2014 by The American Society for Biochemistry and Molecular Biology, Inc.

  10. Spontaneous formation of InGaN nanowall network directly on Si

    Energy Technology Data Exchange (ETDEWEB)

    Soto Rodriguez, P. E. D.; Kumar, Praveen; Gomez, V. J.; Alvi, N. H.; Calleja, E.; Noetzel, R. [Instituto de Sistemas Optoelectronicos y Microtecnologia (ISOM), Universidad Politecnica de Madrid, Ciudad Universitaria s/n, 28040 Madrid (Spain); Manuel, J. M.; Morales, F. M.; Jimenez, J. J.; Garcia, R. [Dep. Ciencia de los Materiales e IM y QI., F. Ciencias, Universidad de Cadiz, 11510-Puerto Real, Cadiz (Spain)

    2013-04-29

    We present the study on epitaxial growth of an InGaN nanowall network directly on Si by plasma-assisted molecular beam epitaxy. Scanning electron microscopy, high-resolution X-ray diffraction, and transmission electron microscopy together with energy-dispersive X-ray analysis infer the crystalline nature of the InGaN nanowall network, oriented along the C-axis, with In composition ranging from pure GaN to 40%. Room temperature photoluminescence is observed, indicating good optical quality. The nanowall network is highly in-plane electrically conductive.

  11. Formation of Robust Multi-Agent Networks through Self-Organizing Random Regular Graphs

    KAUST Repository

    Yasin Yazicioǧlu, A.; Egerstedt, Magnus; Shamma, Jeff S.

    2015-01-01

    Multi-Agent networks are often modeled as interaction graphs, where the nodes represent the agents and the edges denote some direct interactions. The robustness of a multi-Agent network to perturbations such as failures, noise, or malicious attacks largely depends on the corresponding graph. In many applications, networks are desired to have well-connected interaction graphs with relatively small number of links. One family of such graphs is the random regular graphs. In this paper, we present a decentralized scheme for transforming any connected interaction graph with a possibly non-integer average degree of k into a connected random m-regular graph for some m ϵ [k+k ] 2. Accordingly, the agents improve the robustness of the network while maintaining a similar number of links as the initial configuration by locally adding or removing some edges. © 2015 IEEE.

  12. Formation of Robust Multi-Agent Networks through Self-Organizing Random Regular Graphs

    KAUST Repository

    Yasin Yazicioǧlu, A.

    2015-11-25

    Multi-Agent networks are often modeled as interaction graphs, where the nodes represent the agents and the edges denote some direct interactions. The robustness of a multi-Agent network to perturbations such as failures, noise, or malicious attacks largely depends on the corresponding graph. In many applications, networks are desired to have well-connected interaction graphs with relatively small number of links. One family of such graphs is the random regular graphs. In this paper, we present a decentralized scheme for transforming any connected interaction graph with a possibly non-integer average degree of k into a connected random m-regular graph for some m ϵ [k+k ] 2. Accordingly, the agents improve the robustness of the network while maintaining a similar number of links as the initial configuration by locally adding or removing some edges. © 2015 IEEE.

  13. Experimental Demonstration of Mixed Formats and Bit Rates Signal Allocation for Spectrum-flexible Optical Networking

    DEFF Research Database (Denmark)

    Borkowski, Robert; Karinou, Fotini; Angelou, Marianna

    2012-01-01

    We report on an extensive experimental study for adaptive allocation of 16-QAM and QPSK signals inside spectrum flexible heterogeneous superchannel. Physical-layer performance parameters are extracted for use in resource allocation mechanisms of future flexible networks....

  14. Design and Test of the Cross-Format Schema Protocol (XFSP) for Networked Virtual Environments

    National Research Council Canada - National Science Library

    Serin, Ekrem

    2003-01-01

    A Networked Virtual Environment (Net-VE) is a distributed software system in which multiple users interact with each other in real time even though these users may be located around the world Zyda 99...

  15. Direct activation of EXPANSIN14 by LBD18 in the gene regulatory network of lateral root formation in Arabidopsis.

    Science.gov (United States)

    Kim, Jungmook; Lee, Han Woo

    2013-02-01

    Root system architecture is important for plants to adapt to a changing environment. The major determinant of the root system is lateral roots originating from the primary root. The developmental process of lateral root formation can be divided into priming, initiation, primordium development and the emergence of lateral roots, and is well characterized in Arabidopsis. The hormone auxin plays a critical role in lateral root development, and several auxin response modules involving AUXIN RESPONSE FACTORS (ARFs), transcriptional regulators of auxin-regulated genes and Aux/IAA, negative regulators of ARFs, regulate lateral root formation. The LATERAL ORGAN BOUNDARIES DOMAIN/ASYMMETRIC LEAVES2-LIKE (LBD/ASL) gene family encodes a unique class of transcription factors harbouring a conserved plant-specific lateral organ boundary domain and plays a role in lateral organ development of plants including lateral root formation. In our previous study, we showed that LBD18 stimulates lateral root formation in combination with LBD16 downstream of ARF7 and ARF19 during the auxin response. We have recently demonstrated that LBD18 activates expression of EXP14, a gene encoding the cell-wall loosening factor, by directly binding to the EXP14 promoter to promote lateral root emergence. Here we present the molecular function of LBD18 and its gene regulatory network during lateral root formation.

  16. Framework for Explaining the Formation of Knowledge Intensive Entrepreneurial Born Global Firm: Entrepreneurial, Strategic and Network Based Constituents

    Directory of Open Access Journals (Sweden)

    Vytaute Dlugoborskyte

    2017-01-01

    Full Text Available The nature of the knowledge based entrepreneurship relates to its essential reliance on research and development, deployment and maximization of research and development returns via technology development, and its commercialization via venturing. The paper aims to provide the empirically grounded framework for the analysis of the key determinants leading to the formation of R&D intensive entrepreneurial born global firm with a special focus on entrepreneurial firm and network theories. The unit of analysis chosen is the firm, while the focus is set on the firm behavior and strategic choices rather the business conditions per se. The paper aims to propose the definition of a born global firm as a specific form of entrepreneurial firm that forms while combining entrepreneurial, strategy and network constituents in a specific globally oriented constitution. Method of analysis applied is a multiple case study that was applied in order to build evidence on the interplay of strategy, networks and entrepreneurial constituents in the formation of knowledge intensive entrepreneurial born global firm. The small catching up country perspective adds on dynamics of the constituents as the framework and competitive conditions rapidly change in an uncertain direction.

  17. Fetal brain extracellular matrix boosts neuronal network formation in 3D bioengineered model of cortical brain tissue.

    Science.gov (United States)

    Sood, Disha; Chwalek, Karolina; Stuntz, Emily; Pouli, Dimitra; Du, Chuang; Tang-Schomer, Min; Georgakoudi, Irene; Black, Lauren D; Kaplan, David L

    2016-01-01

    The extracellular matrix (ECM) constituting up to 20% of the organ volume is a significant component of the brain due to its instructive role in the compartmentalization of functional microdomains in every brain structure. The composition, quantity and structure of ECM changes dramatically during the development of an organism greatly contributing to the remarkably sophisticated architecture and function of the brain. Since fetal brain is highly plastic, we hypothesize that the fetal brain ECM may contain cues promoting neural growth and differentiation, highly desired in regenerative medicine. Thus, we studied the effect of brain-derived fetal and adult ECM complemented with matricellular proteins on cortical neurons using in vitro 3D bioengineered model of cortical brain tissue. The tested parameters included neuronal network density, cell viability, calcium signaling and electrophysiology. Both, adult and fetal brain ECM as well as matricellular proteins significantly improved neural network formation as compared to single component, collagen I matrix. Additionally, the brain ECM improved cell viability and lowered glutamate release. The fetal brain ECM induced superior neural network formation, calcium signaling and spontaneous spiking activity over adult brain ECM. This study highlights the difference in the neuroinductive properties of fetal and adult brain ECM and suggests that delineating the basis for this divergence may have implications for regenerative medicine.

  18. Frequency Resource Sharing and Allocation Scheme Based on Coalition Formation Game in Hybrid D2D-Cellular Network

    Directory of Open Access Journals (Sweden)

    Qing Ou

    2015-01-01

    Full Text Available A distributed cooperation scheme on frequency resource sharing is proposed to improve the quality of service (QoS in device-to-device (D2D communications underlaying cellular networks. Specifically, we formulate the resource allocation problem as a coalition formation game with transferable utility, in which all users have the incentive to cooperate with some others and form a competitive group to maximize the probability of obtaining their favorite spectrum resources. Taking the cost for coalition formation into account, such as the path loss for data sharing, we prove that the core of the proposed game is empty, which shows the impossibility of grand coalition. Hence, we propose a distributed merge-and-split based coalition formation algorithm based on a new defined Max-Coalition order to effectively solve the coalition game. Compared with the exhaustive search, our algorithm has much lower computer complexity. In addition, we prove that stability and convergence of the proposed algorithm using the concept of a defection function. Finally, the simulation results show that the proposed scheme achieves a suboptimal performance in terms of network sum rate compared with the centralized optimal resource allocation scheme obtained via exhaustive search.

  19. In vitro model of vascularized bone: synergizing vascular development and osteogenesis.

    Directory of Open Access Journals (Sweden)

    Cristina Correia

    Full Text Available Tissue engineering provides unique opportunities for regenerating diseased or damaged tissues using cells obtained from tissue biopsies. Tissue engineered grafts can also be used as high fidelity models to probe cellular and molecular interactions underlying developmental processes. In this study, we co-cultured human umbilical vein endothelial cells (HUVECs and human mesenchymal stem cells (MSCs under various environmental conditions to elicit synergistic interactions leading to the colocalized development of capillary-like and bone-like tissues. Cells were encapsulated at the 1:1 ratio in fibrin gel to screen compositions of endothelial growth medium (EGM and osteogenic medium (OM. It was determined that, to form both tissues, co-cultures should first be supplied with EGM followed by a 1:1 cocktail of the two media types containing bone morphogenetic protein-2. Subsequent studies of HUVECs and MSCs cultured in decellularized, trabecular bone scaffolds for 6 weeks assessed the effects on tissue construct of both temporal variations in growth-factor availability and addition of fresh cells. The resulting grafts were implanted subcutaneously into nude mice to determine the phenotype stability and functionality of engineered vessels. Two important findings resulted from these studies: (i vascular development needs to be induced prior to osteogenesis, and (ii the addition of additional hMSCs at the osteogenic induction stage improves both tissue outcomes, as shown by increased bone volume fraction, osteoid deposition, close proximity of bone proteins to vascular networks, and anastomosis of vascular networks with the host vasculature. Interestingly, these observations compare well with what has been described for native development. We propose that our cultivation system can mimic various aspects of endothelial cell-osteogenic precursor interactions in vivo, and could find utility as a model for studies of heterotypic cellular interactions that

  20. A longitudinal study of organizational formation, innovation adoption, and dissemination activities within the National Drug Abuse Treatment Clinical Trials Network.

    Science.gov (United States)

    Roman, Paul M; Abraham, Amanda J; Rothrauff, Tanja C; Knudsen, Hannah K

    2010-06-01

    The National Institute on Drug Abuse established the National Drug Abuse Treatment Clinical Trials Network (CTN) to conduct trials of promising substance abuse treatment interventions in diverse clinical settings and to disseminate results of these trials. This article focuses on three dimensions of CTN's organizational functioning. First, a longitudinal dataset is used to examine CTN's formation as a network of interorganizational interaction among treatment practitioners and researchers. Data indicate strong relationships of interaction and trust, but a decline in problem-centered interorganizational interaction over time. Second, adoption of buprenorphine and motivational incentives among CTN's affiliated community treatment programs (CTPs) is examined over three waves of data. Although adoption is found to increase with CTPs' CTN participation, there is only modest evidence of widespread penetration and implementation. Third, CTPs' pursuit of the CTN's dissemination goals are examined, indicating that such organizational outreach activities are underway and likely to increase innovation diffusion in the future.

  1. Natural organic matter characterization by HPSEC and its contribution to trihalomethane formation in Athens water supply network.

    Science.gov (United States)

    Samios, Stelios A; Golfinopoulos, Spyros K; Andrzejewski, Przemyslaw; Świetlik, Joanna

    2017-08-24

    Samples from the two main watersheds that provide Athens Water Supply and Sewerage Company (AWSSC) with raw water were examined for Dissolved Organic Carbon (DOC) and for their molecular weight distribution (MWD). In addition, water samples from water treatment plants (WTPs) and from the water supply network were examined for trihalomethane (THMs) levels. The main purpose of this study was to reveal the molecular composition of natural organic matter (NOM) and identify the individual differences between NOM from the two main Athens watersheds. High-performance size exclusion chromatography (HPSEC), a relatively simple technique, was applied to determine different NOM fractions' composition according to molecular weight. Various THM levels in the supply network of Athens are illustrated as a result of the different reservoirs' water qualities, and a suggestion for a limited application of chlorine dioxide is made in order to minimize THM formation.

  2. Vascular ring complicates accidental button battery ingestion.

    Science.gov (United States)

    Mercer, Ronald W; Schwartz, Matthew C; Stephany, Joshua; Donnelly, Lane F; Franciosi, James P; Epelman, Monica

    2015-01-01

    Button battery ingestion can lead to dangerous complications, including vasculoesophageal fistula formation. The presence of a vascular ring may complicate battery ingestion if the battery lodges at the level of the ring and its important vascular structures. We report a 4-year-old boy with trisomy 21 who was diagnosed with a vascular ring at the time of button battery ingestion and died 9 days after presentation due to massive upper gastrointestinal bleeding from esophageal erosion and vasculoesophageal fistula formation. Copyright © 2015 Elsevier Inc. All rights reserved.

  3. Tetrapeptide-coumarin conjugate 3D networks based on hydrogen-bonded charge transfer complexes: gel formation and dye release.

    Science.gov (United States)

    Guo, Zongxia; Gong, Ruiying; Jiang, Yi; Wan, Xiaobo

    2015-08-14

    Oligopeptide-based derivatives are important synthons for bio-based functional materials. In this article, a Gly-(L-Val)-Gly-(L-Val)-coumarin (GVGV-Cou) conjugate was synthesized, which forms 3D networks in ethanol. The gel nanostructures were characterized by UV-vis spectroscopy, FT-IR spectroscopy, X-ray diffraction (XRD), SEM and TEM. It is suggested that the formation of charge transfer (CT) complexes between the coumarin moieties is the main driving force for the gel formation. The capability of the gel to encapsulate and release dyes was explored. Both Congo Red (CR) and Methylene Blue (MB) can be trapped in the CT gel matrix and released over time. The present gel might be used as a functional soft material for guest encapsulation and release.

  4. Comparing global alcohol and tobacco control efforts: network formation and evolution in international health governance.

    Science.gov (United States)

    Gneiting, Uwe; Schmitz, Hans Peter

    2016-04-01

    Smoking and drinking constitute two risk factors contributing to the rising burden of non-communicable diseases in low- and middle-income countries. Both issues have gained increased international attention, but tobacco control has made more sustained progress in terms of international and domestic policy commitments, resources dedicated to reducing harm, and reduction of tobacco use in many high-income countries. The research presented here offers insights into why risk factors with comparable levels of harm experience different trajectories of global attention. The analysis focuses particular attention on the role of dedicated global health networks composed of individuals and organizations producing research and engaging in advocacy on a given health problem. Variation in issue characteristics and the policy environment shape the opportunities and challenges of global health networks focused on reducing the burden of disease. What sets the tobacco case apart was the ability of tobacco control advocates to create and maintain a consensus on policy solutions, expand their reach in low- and middle-income countries and combine evidence-based research with advocacy reaching beyond the public health-centered focus of the core network. In contrast, a similar network in the alcohol case struggled with expanding its reach and has yet to overcome divisions based on competing problem definitions and solutions to alcohol harm. The tobacco control network evolved from a group of dedicated individuals to a global coalition of membership-based organizations, whereas the alcohol control network remains at the stage of a collection of dedicated and like-minded individuals. Published by Oxford University Press in association with The London School of Hygiene and Tropical Medicine © The Author 2016; all rights reserved.

  5. RNAi-mediated downregulation of oral cancer overexpressed 1 (ORAOV1) inhibits vascular endothelial cell proliferation, migration, invasion, and tube formation.

    Science.gov (United States)

    Zhao, Xin; Liu, Dongjuan; Wang, Lili; Wu, Ruiqing; Zeng, Xin; Dan, Hongxia; Ji, Ning; Jiang, Lu; Zhou, Yu; Chen, Qianming

    2016-04-01

    Oral squamous cell carcinoma (OSCC) is one of the top ten tumors threatening human health. Oral cancer overexpressed 1 (ORAOV1) identified within chromosomal region 11q13, one of the most frequently amplified regions in OSCC, has been suggested as a novel candidate oncogene in OSCC, regulating cell cycle, apoptosis, and angiogenesis. In this study, we investigated the role of ORAOV1 in OSCC-induced angiogenesis in vitro. EA.hy926 human endothelial cells were co-cultured with OSCC cells (HSC-3 and SCC-25) transfected with ORAOV1-specific shRNA to downregulate ORAOV1 expression, and analyzed for proliferation, migration, invasion, and tube formation by specific assays. EA.hy926 endothelial cells co-cultured with ORAOV1-deficient OSCC cells exhibited significantly lower proliferation, migration, and invasion, as well as the activity in tube formation compared to that in the control cells. Our results show, for the first time, that ORAOV1 expressed by OSCC cells promotes tube formation by endothelial cells, indicating its involvement in OSCC angiogenesis. Considering the importance of neovascularization in tumor development and metastasis, these findings suggest that targeting ORAOV1 may be a potential therapeutic strategy against OSCC. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  6. Cisco Networking Academy Program for high school students: Formative & summative evaluation

    Science.gov (United States)

    Cranford-Wesley, Deanne

    This study examined the effectiveness of the Cisco Network Technology Program in enhancing students' technology skills as measured by classroom strategies, student motivation, student attitude, and student learning. Qualitative and quantitative methods were utilized to determine the effectiveness of this program. The study focused on two 11th grade classrooms at Hamtramck High School. Hamtramck, an inner-city community located in Detroit, is racially and ethnically diverse. The majority of students speak English as a second language; more than 20 languages are represented in the school district. More than 70% of the students are considered to be economically at risk. Few students have computers at home, and their access to the few computers at school is limited. Purposive sampling was conducted for this study. The sample consisted of 40 students, all of whom were trained in Cisco Networking Technologies. The researcher examined viable learning strategies in teaching a Cisco Networking class that focused on a web-based approach. Findings revealed that the Cisco Networking Academy Program was an excellent vehicle for teaching networking skills and, therefore, helping to enhance computer skills for the participating students. However, only a limited number of students were able to participate in the program, due to limited computer labs and lack of qualified teaching personnel. In addition, the cumbersome technical language posed an obstacle to students' success in networking. Laboratory assignments were preferred by 90% of the students over lecture and PowerPoint presentations. Practical applications, lab projects, interactive assignments, PowerPoint presentations, lectures, discussions, readings, research, and assessment all helped to increase student learning and proficiency and to enrich the classroom experience. Classroom strategies are crucial to student success in the networking program. Equipment must be updated and utilized to ensure that students are

  7. TCR triggering induces the formation of Lck-RACK1-actinin-1 multiprotein network affecting Lck redistribution

    Directory of Open Access Journals (Sweden)

    Ondrej Ballek

    2016-10-01

    Full Text Available The initiation of T-cell signaling is critically dependent on the function of the member of Src family tyrosine kinases (SFKs, Lck. Upon TCR triggering, Lck kinase activity induces the nucleation of signal-transducing hubs that regulate the formation of complex signaling network and cytoskeletal rearrangement. In addition, the delivery of Lck function requires rapid and targeted membrane redistribution, but the mechanism underpinning this process is largely unknown. To gain insight into this process, we considered previously described proteins that could assist in this process via their capacity to interact with kinases and regulate their intracellular translocations. An adaptor protein, Receptor for Activated C Kinase 1 (RACK1, was chosen as a viable option and its capacity to bind Lck and aid the process of activation-induced redistribution of Lck was assessed. Our microscopic observation showed that T-cell activation induces a rapid, concomitant and transient co-redistribution of Lck and RACK1 into the forming immunological synapse. Consistent with this observation, the formation of transient RACK1-Lck complexes were detectable in primary CD4+ T-cells with their maximum levels peaking 10 seconds after TCR-CD4 co-aggregation. Moreover, RACK1 preferentially binds to a pool of kinase active pY394Lck which co-purifies with high molecular weight cellular fractions. The formation of RACK1-Lck complexes depends on functional SH2 and SH3 domains of Lck and includes several other signaling and cytoskeletal elements that transiently bind the complex. Notably, the F-actin-crosslinking protein, α-actinin-1, binds to RACK1 only in the presence of kinase active Lck suggesting that the formation of RACK1-pY394Lck-α-actinin-1 complex serves as a signal module coupling actin cytoskeleton bundling with productive TCR/CD4 triggering. In addition, the treatment of CD4+ T-cells with nocodazole, which disrupts the microtubular network, also blocked the formation

  8. A Comparison of the Nomological Networks Associated With Forced-Choice and Likert Formats of the Narcissistic Personality Inventory.

    Science.gov (United States)

    Miller, Joshua D; Gentile, Brittany; Carter, Nathan T; Crowe, Michael; Hoffman, Brian J; Campbell, W Keith

    2018-01-01

    The Narcissistic Personality Inventory (NPI) is one of the most popular measures of narcissism. However, its use of a forced-choice response set might negatively affect some of its psychometric properties. The purpose of this research was to compare a Likert version of the NPI, in which only the narcissistic response of each pair was given, to the original NPI, in 3 samples of participants (N = 1,109). To this end, we compared the nomological networks of the forced-choice and Likert formats of the NPI in relation to alternative measures of narcissism, narcissistic personality disorder, entitlement, self-esteem, general personality traits (reported by self and informants), interpersonal styles, and general pathological traits included in the DSM-5. The Likert format NPI-total and subscales-manifested similar construct validity to the original forced-choice format across all criteria with only minor differences that seem to be due mainly to the increased reliability and variability found in the Likert NPI Entitlement/Exploitativeness subscale. These results provide evidence that a version of the NPI that employs a Likert format can justifiably be used in place of the original.

  9. Beyond the functional matrix hypothesis: a network null model of human skull growth for the formation of bone articulations.

    Science.gov (United States)

    Esteve-Altava, Borja; Rasskin-Gutman, Diego

    2014-09-01

    Craniofacial sutures and synchondroses form the boundaries among bones in the human skull, providing functional, developmental and evolutionary information. Bone articulations in the skull arise due to interactions between genetic regulatory mechanisms and epigenetic factors such as functional matrices (soft tissues and cranial cavities), which mediate bone growth. These matrices are largely acknowledged for their influence on shaping the bones of the skull; however, it is not fully understood to what extent functional matrices mediate the formation of bone articulations. Aiming to identify whether or not functional matrices are key developmental factors guiding the formation of bone articulations, we have built a network null model of the skull that simulates unconstrained bone growth. This null model predicts bone articulations that arise due to a process of bone growth that is uniform in rate, direction and timing. By comparing predicted articulations with the actual bone articulations of the human skull, we have identified which boundaries specifically need the presence of functional matrices for their formation. We show that functional matrices are necessary to connect facial bones, whereas an unconstrained bone growth is sufficient to connect non-facial bones. This finding challenges the role of the brain in the formation of boundaries between bones in the braincase without neglecting its effect on skull shape. Ultimately, our null model suggests where to look for modified developmental mechanisms promoting changes in bone growth patterns that could affect the development and evolution of the head skeleton. © 2014 Anatomical Society.

  10. Formation of Valley Networks in a Cold and Icy Early Mars Climate: Predictions for Erosion Rates and Channel Morphology

    Science.gov (United States)

    Cassanelli, J.

    2017-12-01

    Mars is host to a diverse array of valley networks, systems of linear-to-sinuous depressions which are widely distributed across the surface and which exhibit branching patterns similar to the dendritic drainage patterns of terrestrial fluvial systems. Characteristics of the valley networks are indicative of an origin by fluvial activity, providing among the most compelling evidence for the past presence of flowing liquid water on the surface of Mars. Stratigraphic and crater age dating techniques suggest that the formation of the valley networks occurred predominantly during the early geologic history of Mars ( 3.7 Ga). However, whether the valley networks formed predominantly by rainfall in a relatively warm and wet early Mars climate, or by snowmelt and episodic rainfall in an ambient cold and icy climate, remains disputed. Understanding the formative environment of the valley networks will help distinguish between these warm and cold end-member early Mars climate models. Here we test a conceptual model for channel incision and evolution under cold and icy conditions with a substrate characterized by the presence of an ice-free dry active layer and subjacent ice-cemented regolith, similar to that found in the Antarctic McMurdo Dry Valleys. We implement numerical thermal models, quantitative erosion and transport estimates, and morphometric analyses in order to outline predictions for (1) the precise nature and structure of the substrate, (2) fluvial erosion/incision rates, and (3) channel morphology. Model predictions are compared against morphologic and morphometric observational data to evaluate consistency with the assumed cold climate scenario. In the cold climate scenario, the substrate is predicted to be characterized by a kilometers-thick globally-continuous cryosphere below a 50-100 meter thick desiccated ice-free zone. Initial results suggest that, with the predicted substrate structure, fluvial channel erosion and morphology in a cold early Mars

  11. Formation of interfacial network structure via photo-crosslinking in carbon fiber/epoxy composites

    Directory of Open Access Journals (Sweden)

    S. H. Deng

    2014-07-01

    Full Text Available A series of diblock copolymers (poly(n-butylacrylate-co-poly(2-hydroxyethyl acrylate-b-poly(glycidyl methacrylate ((PnBA-co-PHEA-b-PGMA, containing a random copolymer block PnBA-co-PHEA, were successfully synthesized by atom transfer radical polymerization (ATRP. After being chemically grafted onto carbon fibers, the photosensitive methacrylic groups were introduced into the random copolymer, giving a series of copolymers (poly(n-butylacrylate-co-poly(2-methacryloyloxyethyl acrylate-b-poly(glycidyl methacrylate((PnBA-co-PMEA-b-PGMA. Dynamic mechanical analysis indicated that the random copolymer block after ultraviolet (UV irradiation was a lightly crosslinked polymer and acted as an elastomer, forming a photo-crosslinked network structure at the interface of carbon fiber/epoxy composites. Microbond test showed that such an interfacial network structure greatly improved the cohesive strength and effectively controlled the deformation ability of the flexible interlayer. Furthermore, three kinds of interfacial network structures, i physical crosslinking by H-bonds, ii chemical crosslinking by photopolymerization, and iii interpenetrating crosslinked network by photopolymerization and epoxy curing reaction were received in carbon fiber/epoxy composite, depending on the various preparation processes.

  12. Kinetic limitation in the formation of end-linked elastomer networks

    Czech Academy of Sciences Publication Activity Database

    Meissner, Bohumil; Matějka, Libor

    2005-01-01

    Roč. 46, č. 24 (2005), s. 10618-10625 ISSN 0032-3861 R&D Projects: GA ČR GA203/05/2252 Keywords : end-linked elastomer networks * effect of stoichiometry * kinetic limitations Subject RIV: CD - Macromolecular Chemistry Impact factor: 2.849, year: 2005

  13. Promoting Cognitive Health: A Formative Research Collaboration of the Healthy Aging Research Network

    Science.gov (United States)

    Laditka, James N.; Beard, Renee L.; Bryant, Lucinda L.; Fetterman, David; Hunter, Rebecca; Ivey, Susan; Logsdon, Rebecca G.; Sharkey, Joseph R.; Wu, Bei

    2009-01-01

    Purpose: Evidence suggests that healthy lifestyles may help maintain cognitive health. The Prevention Research Centers Healthy Aging Research Network, 9 universities collaborating with their communities and the Centers for Disease Control and Prevention, is conducting a multiyear research project, begun in 2005, to understand how to translate this…

  14. Imaging after vascular gene therapy

    International Nuclear Information System (INIS)

    Manninen, Hannu I.; Yang, Xiaoming

    2005-01-01

    Targets for cardiovascular gene therapy currently include limiting restenosis after balloon angioplasty and stent placement, inhibiting vein bypass graft intimal hyperplasia/stenosis, therapeutic angiogenesis for cardiac and lower-limb ischemia, and prevention of thrombus formation. While catheter angiography is still standard method to follow-up vascular gene transfer, other modern imaging techniques, especially intravascular ultrasound (IVUS), magnetic resonance (MR), and positron emission tomography (PET) imaging provide complementary information about the therapeutic effect of vascular gene transfer in humans. Although molecular imaging of therapeutic gene expression in the vasculatures is still in its technical development phase, it has already offered basic medical science an extremely useful in vivo evaluation tool for non- or minimally invasive imaging of vascular gene therapy

  15. An Ongoing Role of α-Calcitonin Gene–Related Peptide as Part of a Protective Network Against Hypertension, Vascular Hypertrophy, and Oxidative Stress

    DEFF Research Database (Denmark)

    Smillie, Sarah-Jane; King, Ross; Kodji, Xenia

    2014-01-01

    α-Calcitonin gene-related peptide (αCGRP) is a vasodilator, but there is limited knowledge of its long-term cardiovascular protective influence. We hypothesized that αCGRP protects against the onset and development of angiotensin II-induced hypertension and have identified protective mechanisms......CGRP knockout mice. These results demonstrate the ongoing upregulation of αCGRP at the levels of both conduit and resistance vessels in vascular tissue in a model of hypertension and the direct association of this with protection against aortic vascular hypertrophy and fibrosis. This upregulation is maintained...... at a time when expression of aortic endothelial NO synthase and antioxidant defense genes have subsided, in keeping with the concept that the protective influence of αCGRP in hypertension may have been previously underestimated....

  16. Vascular function in health, hypertension, and diabetes

    DEFF Research Database (Denmark)

    Nyberg, Michael Permin; Gliemann, Lasse; Hellsten, Ylva

    2015-01-01

    muscle, which can affect muscle function. Central aspects in the vascular impairments are alterations in the formation of prostacyclin, the bioavailability of NO and an increased formation of vasoconstrictors and reactive oxygen species (ROS). Regular physical activity effectively improves vascular......, the increase in muscle blood flow required for oxygen supply during exercise is achieved through a substantial increase in vasodilators locally formed in the active muscle tissue that overcome the vasoconstrictor signals. Most of the vasodilator signals are mediated via endothelial cells, which lead...... to the formation of vasodilators such as nitric oxide (NO) and prostacyclin. In essential hypertension and type II diabetes, the endothelial function and regulation of vascular tone is impaired with consequent increases in peripheral vascular resistance and inadequate regulation of oxygen supply to the skeletal...

  17. Dominant negative insulin-like growth factor-1 receptor inhibits neointimal formation through suppression of vascular smooth muscle cell migration and proliferation, and induction of apoptosis

    International Nuclear Information System (INIS)

    Lim, Hyun-Joung; Park, Hyun-Young; Ko, Young-Guk; Lee, Sea-Hyoung; Cho, Seung-Yeon; Lee, Eun Jig; Jameson, J. Larry; Jang, Yangsoo

    2004-01-01

    Blocking of the IGF-1 signaling pathway targeting the IGF-1 receptor (IGF-1R) provides a potential treatment strategy for restenosis. In this study, we have examined the effects of a dominant negative IGF-1R (IGF-1Rt) on primary rat VSMCs in vitro and on injured rat carotid artery in vivo. Ad/IGF-1Rt infection inhibited VSMC migration and proliferation, and it also induced apoptosis by inhibiting phosphorylation of Akt and phosphorylation of ERK1/2. Consistent with the anti-proliferative and apoptotic effects in vitro, the Ad/IGF-1Rt infection markedly reduced neointimal formation in carotid injury model. Ad/IGF-1Rt treated carotid arteries exhibited a suppressed proliferation index, PCNA expression, and also were stained positive for TUNEL assay. These results indicate that a dominant negative IGF-1R has the potential to reduce neointimal formation of injured rats' carotid arteries. The delivery of dominant negative IGF-1R by adenoviral or other vectors may provide a useful strategy for inhibiting restenosis after angioplasty

  18. Decentralized formation of random regular graphs for robust multi-agent networks

    KAUST Repository

    Yazicioglu, A. Yasin

    2014-12-15

    Multi-agent networks are often modeled via interaction graphs, where the nodes represent the agents and the edges denote direct interactions between the corresponding agents. Interaction graphs have significant impact on the robustness of networked systems. One family of robust graphs is the random regular graphs. In this paper, we present a locally applicable reconfiguration scheme to build random regular graphs through self-organization. For any connected initial graph, the proposed scheme maintains connectivity and the average degree while minimizing the degree differences and randomizing the links. As such, if the average degree of the initial graph is an integer, then connected regular graphs are realized uniformly at random as time goes to infinity.

  19. Dielectric monitoring of carbon nanotube network formation in curing thermosetting nanocomposites

    Energy Technology Data Exchange (ETDEWEB)

    Battisti, A; Skordos, A A; Partridge, I K, E-mail: a.battisti@cranfield.ac.u [Composites Centre, School of Applied Sciences, Cranfield University, Cranfield, Bedfordshire, MK43 0AL (United Kingdom)

    2009-08-07

    This paper focuses on monitoring of carbon nanotube (CNT) network development during the cure of unsaturated polyester nanocomposites by means of electrical impedance spectroscopy. A phenomenological model of the dielectric response is developed using equivalent circuit analysis. The model comprises two parallel RC elements connected in series, each of them giving rise to a semicircular arc in impedance complex plane plots. An established inverse modelling methodology is utilized for the estimation of the parameters of the corresponding equivalent circuit. This allows a quantification of the evolution of two separate processes corresponding to the two parallel RC elements. The high frequency process, which is attributed to CNT aggregates, shows a monotonic decrease in characteristic time during the cure. In contrast, the low frequency process, which corresponds to inter-aggregate phenomena, shows a more complex behaviour explained by the interplay between conductive network development and the cross-linking of the polymer.

  20. Dielectric monitoring of carbon nanotube network formation in curing thermosetting nanocomposites

    Science.gov (United States)

    Battisti, A.; Skordos, A. A.; Partridge, I. K.

    2009-08-01

    This paper focuses on monitoring of carbon nanotube (CNT) network development during the cure of unsaturated polyester nanocomposites by means of electrical impedance spectroscopy. A phenomenological model of the dielectric response is developed using equivalent circuit analysis. The model comprises two parallel RC elements connected in series, each of them giving rise to a semicircular arc in impedance complex plane plots. An established inverse modelling methodology is utilized for the estimation of the parameters of the corresponding equivalent circuit. This allows a quantification of the evolution of two separate processes corresponding to the two parallel RC elements. The high frequency process, which is attributed to CNT aggregates, shows a monotonic decrease in characteristic time during the cure. In contrast, the low frequency process, which corresponds to inter-aggregate phenomena, shows a more complex behaviour explained by the interplay between conductive network development and the cross-linking of the polymer.

  1. Dielectric monitoring of carbon nanotube network formation in curing thermosetting nanocomposites

    International Nuclear Information System (INIS)

    Battisti, A; Skordos, A A; Partridge, I K

    2009-01-01

    This paper focuses on monitoring of carbon nanotube (CNT) network development during the cure of unsaturated polyester nanocomposites by means of electrical impedance spectroscopy. A phenomenological model of the dielectric response is developed using equivalent circuit analysis. The model comprises two parallel RC elements connected in series, each of them giving rise to a semicircular arc in impedance complex plane plots. An established inverse modelling methodology is utilized for the estimation of the parameters of the corresponding equivalent circuit. This allows a quantification of the evolution of two separate processes corresponding to the two parallel RC elements. The high frequency process, which is attributed to CNT aggregates, shows a monotonic decrease in characteristic time during the cure. In contrast, the low frequency process, which corresponds to inter-aggregate phenomena, shows a more complex behaviour explained by the interplay between conductive network development and the cross-linking of the polymer.

  2. Self-organized pattern formation of biomolecules at silicon surfaces: Intended application of a dislocation network

    International Nuclear Information System (INIS)

    Kittler, M.; Yu, X.; Vyvenko, O.F.; Birkholz, M.; Seifert, W.; Reiche, M.; Wilhelm, T.; Arguirov, T.; Wolff, A.; Fritzsche, W.; Seibt, M.

    2006-01-01

    Defined placement of biomolecules at Si surfaces is a precondition for a successful combination of Si electronics with biological applications. We aim to realize this by Coulomb interaction of biomolecules with dislocations in Si. The dislocations form charged lines and they will be surrounded with a space charge region being connected with an electric field. The electric stray field in a solution of biomolecules, caused by dislocations located close to the Si surface, was estimated to yield values up to few kVcm -1 . A regular dislocation network can be formed by wafer direct bonding at the interface between the bonded wafers in case of misorientation. The adjustment of misorientation allows the variation of the distance between dislocations in a range from 10 nm to a few μm. This is appropriate for nanobiotechnology dealing with protein or DNA molecules with sizes in the nm and lower μm range. Actually, we achieved a distance between the dislocations of 10-20 nm. Also the existence of a distinct electric field formed by the dislocation network was demonstrated by the technique of the electron-beam-induced current (EBIC). Because of the relatively short range of the field, the dislocations have to be placed close to the surface. We positioned the dislocation network in an interface being 200 nm parallel to the Si surface by layer transfer techniques using hydrogen implantation and bonding. Based on EBIC and luminescence data we postulate a barrier of the dislocations at the as bonded interface < 100 meV. We plan to dope the dislocations with metal atoms to increase the electric field. We demonstrated that regular periodic dislocation networks close to the Si surface formed by bonding are realistic candidates for self-organized placing of biomolecules. Experiments are underway to test whether biomolecules decorate the pattern of the dislocation lines

  3. Vasohibin inhibits angiogenic sprouting in vitro and supports vascular maturation processes in vivo

    International Nuclear Information System (INIS)

    Kern, Johann; Steurer, Michael; Gastl, Günther; Gunsilius, Eberhard; Untergasser, Gerold

    2009-01-01

    The murine homologue of human vasohibin (mVASH1), a putative antiangiogenic protein, was investigated for its effects on in vitro and in vivo angiogenesis. Cell growth and migration were analyzed in murine fibroblasts, smooth muscle cells and endothelial cells. Angiogenic sprouting was studied in human umbilical vein endothelial cells (HUVECs) in the spheroid sprouting assay. In vivo effects on blood vessel formation were investigated in the chorioallantoic membrane (CAM) assay and in the C57BL/6 melanoma xenograft model. Purified murine and human VASH1 protein induced apoptosis of murine fibroblasts in vitro, but not of vascular aortic smooth muscle cells (AoSMC) or endothelial cells. Adenoviral overexpression of murine and human VASH1 inhibited capillary sprouting of HUVECs in the spheroid assay. Administration of recombinant murine and human VASH1 inhibited growth of large vessels in the CAM assay and promoted the formation of a dense, fine vascular network. Murine VASH1-overexpressing B16F10 melanomas displayed a reduction in large vessels and vascular area. Moreover, tumors showed more microvessels that stained positive for the mural cell markers α-smooth muscle cell actin (ASMA) and proteoglycan (NG2). Our data imply that murine VASH1 causes angiogenic remodelling by inhibiting angiogenic sprouting and large vessel growth, thereby supporting the formation of a vascular bed consisting predominantly of mature microvessels

  4. The Formation of the Eastern Africa Rabies Network: A Sub-Regional Approach to Rabies Elimination.

    Science.gov (United States)

    Pieracci, Emily G; Scott, Terence P; Coetzer, Andre; Athman, Mwatondo; Mutembei, Arithi; Kidane, Abraham Haile; Bekele, Meseret; Ayalew, Girma; Ntegeyibizaza, Samson; Assenga, Justine; Markalio, Godson; Munyua, Peninah; Nel, Louis H; Blanton, Jesse

    2017-01-01

    International rabies networks have been formed in many of the canine-rabies endemic regions around the world to create unified and directed regional approaches towards elimination. The aim of the first sub-regional Eastern Africa rabies network meeting, which included Kenya, Ethiopia, Tanzania, Rwanda, and Uganda, was to discuss how individual country strategies could be coordinated to address the unique challenges that are faced within the network. The Stepwise Approach towards Rabies Elimination and the Global Dog Rabies Elimination Pathway tool were used to stimulate discussion and planning to achieve the elimination of canine-mediated human rabies by 2030. Our analysis estimated a total dog population of 18.3 million dogs in the Eastern Africa region. The current dog vaccination coverage was estimated to be approximately 5% (915,000 dogs), with an estimated 4910 vaccinators available. Assuming that every vaccinator performs rabies vaccination, this equated to each vaccinator currently vaccinating 186 dogs per year, whilst the target would be to vaccinate 2609 dogs every year for the community to reach 70% coverage. In order to achieve the World Health Organization-recommended 70% vaccination coverage, an additional 11 million dogs need to be vaccinated each year, pointing to an average annual shortfall of $ 23 million USD in current spending to achieve elimination by 2030 across the region. Improved vaccination efficiency within the region could be achieved by improving logistics and/or incorporating multiple vaccination methods to increase vaccinator efficiency, and could serve to reduce the financial burden associated with rabies elimination. Regional approaches to rabies control are of value, as neighboring countries can share their unique challenges while, at the same time, common approaches can be developed and resource-saving strategies can be implemented.

  5. Vascular Gene Expression: A Hypothesis

    Directory of Open Access Journals (Sweden)

    Angélica Concepción eMartínez-Navarro

    2013-07-01

    Full Text Available The phloem is the conduit through which photoassimilates are distributed from autotrophic to heterotrophic tissues and is involved in the distribution of signaling molecules that coordinate plant growth and responses to the environment. Phloem function depends on the coordinate expression of a large array of genes. We have previously identified conserved motifs in upstream regions of the Arabidopsis genes, encoding the homologs of pumpkin phloem sap mRNAs, displaying expression in vascular tissues. This tissue-specific expression in Arabidopsis is predicted by the overrepresentation of GA/CT-rich motifs in gene promoters. In this work we have searched for common motifs in upstream regions of the homologous genes from plants considered to possess a primitive vascular tissue (a lycophyte, as well as from others that lack a true vascular tissue (a bryophyte, and finally from chlorophytes. Both lycophyte and bryophyte display motifs similar to those found in Arabidopsis with a significantly low E-value, while the chlorophytes showed either a different conserved motif or no conserved motif at all. These results suggest that these same genes are expressed coordinately in non- vascular plants; this coordinate expression may have been one of the prerequisites for the development of conducting tissues in plants. We have also analyzed the phylogeny of conserved proteins that may be involved in phloem function and development. The presence of CmPP16, APL, FT and YDA in chlorophytes suggests the recruitment of ancient regulatory networks for the development of the vascular tissue during evolution while OPS is a novel protein specific to vascular plants.

  6. A Comparison of Alternative Distributed Dynamic Cluster Formation Techniques for Industrial Wireless Sensor Networks.

    Science.gov (United States)

    Gholami, Mohammad; Brennan, Robert W

    2016-01-06

    In this paper, we investigate alternative distributed clustering techniques for wireless sensor node tracking in an industrial environment. The research builds on extant work on wireless sensor node clustering by reporting on: (1) the development of a novel distributed management approach for tracking mobile nodes in an industrial wireless sensor network; and (2) an objective comparison of alternative cluster management approaches for wireless sensor networks. To perform this comparison, we focus on two main clustering approaches proposed in the literature: pre-defined clusters and ad hoc clusters. These approaches are compared in the context of their reconfigurability: more specifically, we investigate the trade-off between the cost and the effectiveness of competing strategies aimed at adapting to changes in the sensing environment. To support this work, we introduce three new metrics: a cost/efficiency measure, a performance measure, and a resource consumption measure. The results of our experiments show that ad hoc clusters adapt more readily to changes in the sensing environment, but this higher level of adaptability is at the cost of overall efficiency.

  7. Government Agency and Trust in the Formation and Transformation of Interorganizational Entrepreneurial Networks

    DEFF Research Database (Denmark)

    Neergaard, Helle; Ulhøi, John Parm

    2006-01-01

    This article examines the role of trust and government agency in the creation and evolution of interoganizational cooperation among entrepreneurial ventures in general and the influence of trust on development trajectories in particular. The multiple-case approach used draws on five in-depth case...... studies adopting a focal firm perspective. Trust is shown to play a critical role in the formation, maintenance and transformation of interorganizational cooperative relationships whereas its absence results in discontinuation. Moreover, the results suggest that government agency may unintentionally...

  8. Cell sheet engineering using the stromal vascular fraction of adipose tissue as a vascularization strategy.

    Science.gov (United States)

    Costa, Marina; Cerqueira, Mariana T; Santos, Tírcia C; Sampaio-Marques, Belém; Ludovico, Paula; Marques, Alexandra P; Pirraco, Rogério P; Reis, Rui L

    2017-06-01

    Current vascularization strategies for Tissue Engineering constructs, in particular cell sheet-based, are limited by time-consuming and expensive endothelial cell isolation and/or by the complexity of using extrinsic growth factors. Herein, we propose an alternative strategy using angiogenic cell sheets (CS) obtained from the stromal vascular fraction (SVF) of adipose tissue that can be incorporated into more complex constructs. Cells from the SVF were cultured in normoxic and hypoxic conditions for up to 8days in the absence of extrinsic growth factors. Immunocytochemistry against CD31 and CD146 revealed spontaneous organization in capillary-like structures, more complex after hypoxic conditioning. Inhibition of HIF-1α pathway hindered capillary-like structure formation in SVF cells cultured in hypoxia, suggesting a role of HIF-1α. Moreover, hypoxic SVF cells showed a trend for increased secretion of angiogenic factors, which was reflected in increased network formation by endothelial cells cultured on matrigel using that conditioned medium. In vivo implantation of SVF CS in a mouse hind limb ischemia model revealed that hypoxia-conditioned CS led to improved restoration of blood flow. Both in vitro and in vivo data suggest that SVF CS can be used as simple and cost-efficient tools to promote functional vascularization of TE constructs. Neovascularization after implantation is a major obstacle for producing clinically viable cell sheet-based tissue engineered constructs. Strategies using endothelial cells and extrinsic angiogenic growth factors are expensive and time consuming and may raise concerns of tumorigenicity. In this manuscript, we describe a simplified approach using angiogenic cell sheets fabricated from the stromal vascular fraction of adipose tissue. The strong angiogenic behavior of these cell sheets, achieved without the use of external growth factors, was further stimulated by low oxygen culture. When implanted in an in vivo model of hind limb

  9. The formation of space network in structure of polyallyl cinnamates under UV- and γ-irradiation

    International Nuclear Information System (INIS)

    Yagudeev, T.

    2003-01-01

    Influence of UV- and γ-irradiation on polyallyl cinnamates (PAC) structure are investigated. UV-irradiation of polymers samples carried out by lamp PRK-2 at 25-30 deg. C.; 60 Co was used for γ-irradiation: mean value of dose power - 50 μR/s; average energy of γ-quantum E γ =1.25 MeV. It was shown that under various kinds of irradiation polyallyl cinnamates forms space networks and samples of PAC kept itself physico-mechanical properties (light transparent - 90 %), or increase its (microhardness reach 150 %). It can be concluded that such polymers may find application for creation of elements of laser optics

  10. Segregation of sphingolipids and sterols during formation of secretory vesicles at the trans-Golgi network

    DEFF Research Database (Denmark)

    Klemm, Robin W; Ejsing, Christer S.; Surma, Michal A

    2009-01-01

    The trans-Golgi network (TGN) is the major sorting station in the secretory pathway of all eukaryotic cells. How the TGN sorts proteins and lipids to generate the enrichment of sphingolipids and sterols at the plasma membrane is poorly understood. To address this fundamental question in membrane...... trafficking, we devised an immunoisolation procedure for specific recovery of post-Golgi secretory vesicles transporting a transmembrane raft protein from the TGN to the cell surface in the yeast Saccharomyces cerevisiae. Using a novel quantitative shotgun lipidomics approach, we could demonstrate that TGN...... than the late Golgi membrane, as measured by C-Laurdan spectrophotometry, strongly suggests that lipid rafts play a role in the TGN-sorting machinery....

  11. The Formation of the Concept of Knowledge Potencial in Networking Society

    Directory of Open Access Journals (Sweden)

    Ilona Skačkauskienė

    2015-05-01

    Full Text Available As the information society is gradually transforming into the knowledge society, it is affecting not only consumer preferences and needs but also the changes in corporate activities. Both corporate performance and potential depend on the ability to evaluate, manage and develop available knowledge. Systematic and purposeful application of knowledge gives advantage to companies, whereas personnel knowledge, ideas and skills serve as an impetus of a successful organisation. The article offers a critical view of the concept of knowledge used by researchers and introduces a new definition, employs a new concept of knowledge potential that combines the knowledge of all types and is based on various analysed knowledge types, and assesses the concept of networking and its importance to knowledge potential.

  12. Probability of conductive bond formation in a percolating network of nanowires with fusible tips

    Science.gov (United States)

    Rykaczewski, Konrad; Wang, Robert Y.

    2018-03-01

    Meeting the heat dissipation demands of microelectronic devices requires development of polymeric composites with high thermal conductivity. This property is drastically improved by percolation networks of metallic filler particles that have their particle-to-particle contact resistances reduced through thermal or electromagnetic fusing. However, composites with fused metallic fillers are electrically conductive, which prevents their application within the chip-board and the inter-chip gaps. Here, we propose that electrically insulating composites for these purposes can be achieved by the application of fusible metallic coatings to the tips of nanowires with thermally conductive but electrically insulating cores. We derive analytical models that relate the ratio of the coated and total nanowire lengths to the fraction of fused, and thus conductive, bonds within percolating networks of these structures. We consider two types of materials for these fusible coatings. First, we consider silver-like coatings, which form only conductive bonds when contacting the silver-like coating of another nanowire. Second, we consider liquid metal-like coatings, which form conductive bonds regardless of whether they contact a coated or an uncoated segment of another nanowire. These models were validated using Monte Carlo simulations, which also revealed that electrical short-circuiting is highly unlikely until most of the wire is coated. Furthermore, we demonstrate that switching the tip coating from silver- to liquid metal-like materials can double the fraction of conductive bonds. Consequently, this work provides motivation to develop scalable methods for fabrication of the hybrid liquid-coated nanowires, whose dispersion in a polymer matrix is predicted to yield highly thermally conductive but electrically insulating composites.

  13. Radiotherapy in combination with vascular-targeted therapies

    International Nuclear Information System (INIS)

    Ciric, Eva; Sersa, Gregor

    2010-01-01

    Given the critical role of tumor vasculature in tumor development, considerable efforts have been spent on developing therapeutic strategies targeting the tumor vascular network. A variety of agents have been developed, with two general approaches being pursued. Antiangiogenic agents (AAs) aim to interfere with the process of angiogenesis, preventing new tumor blood vessel formation. Vascular-disrupting agents (VDAs) target existing tumor vessels causing tumor ischemia and necrosis. Despite their great therapeutic potential, it has become clear that their greatest clinical utility may lie in combination with conventional anticancer therapies. Radiotherapy is a widely used treatment modality for cancer with its distinct therapeutic challenges. Thus, combining the two approaches seems reasonable. Strong biological rationale exist for combining vascular-targeted therapies with radiation. AAs and VDAs were shown to alter the tumor microenvironment in such a way as to enhance responses to radiation. The results of preclinical and early clinical studies have confirmed the therapeutic potential of this new treatment strategy in the clinical setting. However, concerns about increased normal tissue toxicity, have been raised

  14. Statistical Characterization of River and Channel Network Formation in Intermittently Flowing Vortex Systems.

    Science.gov (United States)

    Olson, C. J.; Reichhardt, C.; Nori, F.

    1997-03-01

    Vortices moving in dirty superconductors can form intricate flow patterns, resembling fluid rivers, as they interact with the pinning landscape (F. Nori, Science 271), 1373 (1996).. Weaker pinning produces relatively straight nori>vortex channels, while stronger pinning results in the formation of one or more winding channels that carry all flow. This corresponds to a crossover from elastic flow to plastic flow as the pinning strength is increased. For several pinning parameters, we find the fractal dimension of the channels that form, the vortex trail density, the distance travelled by vortices as they pass through the sample, the branching ratio, the sinuosity, and the size distribution of the rivers, and we compare our rivers with physical rivers that follow Horton's laws.

  15. Network topology for the formation of solvated electrons in binary CaO–Al2O3 composition glasses

    Science.gov (United States)

    Akola, Jaakko; Kohara, Shinji; Ohara, Koji; Fujiwara, Akihiko; Watanabe, Yasuhiro; Masuno, Atsunobu; Usuki, Takeshi; Kubo, Takashi; Nakahira, Atsushi; Nitta, Kiyofumi; Uruga, Tomoya; Weber, J. K. Richard; Benmore, Chris J.

    2013-01-01

    Glass formation in the CaO–Al2O3 system represents an important phenomenon because it does not contain typical network-forming cations. We have produced structural models of CaO–Al2O3 glasses using combined density functional theory–reverse Monte Carlo simulations and obtained structures that reproduce experiments (X-ray and neutron diffraction, extended X-ray absorption fine structure) and result in cohesive energies close to the crystalline ground states. The O–Ca and O–Al coordination numbers are similar in the eutectic 64 mol % CaO (64CaO) glass [comparable to 12CaO·7Al2O3 (C12A7)], and the glass structure comprises a topologically disordered cage network with large-sized rings. This topologically disordered network is the signature of the high glass-forming ability of 64CaO glass and high viscosity in the melt. Analysis of the electronic structure reveals that the atomic charges for Al are comparable to those for Ca, and the bond strength of Al–O is stronger than that of Ca–O, indicating that oxygen is more weakly bound by cations in CaO-rich glass. The analysis shows that the lowest unoccupied molecular orbitals occurs in cavity sites, suggesting that the C12A7 electride glass [Kim SW, Shimoyama T, Hosono H (2011) Science 333(6038):71–74] synthesized from a strongly reduced high-temperature melt can host solvated electrons and bipolarons. Calculations of 64CaO glass structures with few subtracted oxygen atoms (additional electrons) confirm this observation. The comparable atomic charges and coordination of the cations promote more efficient elemental mixing, and this is the origin of the extended cage structure and hosted solvated (trapped) electrons in the C12A7 glass. PMID:23723350

  16. Prediction of water formation temperature in natural gas dehydrators using radial basis function (RBF neural networks

    Directory of Open Access Journals (Sweden)

    Tatar Afshin

    2016-03-01

    Full Text Available Raw natural gases usually contain water. It is very important to remove the water from these gases through dehydration processes due to economic reasons and safety considerations. One of the most important methods for water removal from these gases is using dehydration units which use Triethylene glycol (TEG. The TEG concentration at which all water is removed and dew point characteristics of mixture are two important parameters, which should be taken into account in TEG dehydration system. Hence, developing a reliable and accurate model to predict the performance of such a system seems to be very important in gas engineering operations. This study highlights the use of intelligent modeling techniques such as Multilayer perceptron (MLP and Radial Basis Function Neural Network (RBF-ANN to predict the equilibrium water dew point in a stream of natural gas based on the TEG concentration of stream and contractor temperature. Literature data set used in this study covers temperatures from 10 °C to 80 °C and TEG concentrations from 90.000% to 99.999%. Results showed that both models are accurate in prediction of experimental data and the MLP model gives more accurate predictions compared to RBF model.

  17. How pattern formation in ring networks of excitatory and inhibitoryspiking neurons depends on the input current regime

    Directory of Open Access Journals (Sweden)

    Birgit eKriener

    2014-01-01

    Full Text Available Pattern formation, i.e., the generation of an inhomogeneous spatial activity distribution in a dynamical system with translation invariant structure, is a well-studied phenomenon in neuronal network dynamics,specifically in neural field models. These are population models to describe the spatio-temporal dynamics of large groups of neurons in terms of macroscopic variables such as population firing rates. Though neural field models are often deduced from and equipped with biophysically meaningfulproperties, a direct mapping to simulations of individual spiking neuron populations is rarely considered. Neurons have a distinct identity defined by their action on their postsynaptic targets. In its simplest form they act either excitatorily or inhibitorily.When the distribution of neuron identities is assumed to be periodic, pattern formation can be observed, given the coupling strength is supercritical, i.e., larger than a critical weight. We find that this critical weight is strongly dependent on the characteristics of the neuronal input, i.e., depends on whether neurons are mean- orfluctuation driven, and different limits in linearizing the full non-linear system apply in order to assess stability.In particular, if neurons are mean-driven, the linearization has a very simple form and becomesindependent of both the fixed point firing rate and the variance of the input current, while in the very strongly fluctuation-driven regime the fixed point rate, as well as the input mean and variance areimportant parameters in the determination of the critical weight.We demonstrate that interestingly even in ``intermediate'' regimes, when the system is technically fluctuation-driven, the simple linearization neglecting the variance of the input can yield the better prediction of the critical couplingstrength. We moreover analyze the effects of structural randomness by rewiring individualsynapses or redistributing weights, as well as coarse-graining on pattern

  18. How pattern formation in ring networks of excitatory and inhibitory spiking neurons depends on the input current regime.

    Science.gov (United States)

    Kriener, Birgit; Helias, Moritz; Rotter, Stefan; Diesmann, Markus; Einevoll, Gaute T

    2013-01-01

    Pattern formation, i.e., the generation of an inhomogeneous spatial activity distribution in a dynamical system with translation invariant structure, is a well-studied phenomenon in neuronal network dynamics, specifically in neural field models. These are population models to describe the spatio-temporal dynamics of large groups of neurons in terms of macroscopic variables such as population firing rates. Though neural field models are often deduced from and equipped with biophysically meaningful properties, a direct mapping to simulations of individual spiking neuron populations is rarely considered. Neurons have a distinct identity defined by their action on their postsynaptic targets. In its simplest form they act either excitatorily or inhibitorily. When the distribution of neuron identities is assumed to be periodic, pattern formation can be observed, given the coupling strength is supracritical, i.e., larger than a critical weight. We find that this critical weight is strongly dependent on the characteristics of the neuronal input, i.e., depends on whether neurons are mean- or fluctuation driven, and different limits in linearizing the full non-linear system apply in order to assess stability. In particular, if neurons are mean-driven, the linearization has a very simple form and becomes independent of both the fixed point firing rate and the variance of the input current, while in the very strongly fluctuation-driven regime the fixed point rate, as well as the input mean and variance are important parameters in the determination of the critical weight. We demonstrate that interestingly even in "intermediate" regimes, when the system is technically fluctuation-driven, the simple linearization neglecting the variance of the input can yield the better prediction of the critical coupling strength. We moreover analyze the effects of structural randomness by rewiring individual synapses or redistributing weights, as well as coarse-graining on the formation of

  19. Trace elements during primordial plexiform network formation in human cerebral organoids

    Directory of Open Access Journals (Sweden)

    Rafaela C. Sartore

    2017-02-01

    Full Text Available Systematic studies of micronutrients during brain formation are hindered by restrictions to animal models and adult post-mortem tissues. Recently, advances in stem cell biology have enabled recapitulation of the early stages of human telencephalon development in vitro. In the present work, we analyzed cerebral organoids derived from human pluripotent stem cells by synchrotron radiation X-ray fluorescence in order to measure biologically valuable micronutrients incorporated and distributed into the exogenously developing brain. Our findings indicate that elemental inclusion in organoids is consistent with human brain tissue and involves P, S, K, Ca, Fe and Zn. Occurrence of different concentration gradients also suggests active regulation of elemental transmembrane transport. Finally, the analysis of pairs of elements shows interesting elemental interaction patterns that change from 30 to 45 days of development, suggesting short- or long-term associations, such as storage in similar compartments or relevance for time-dependent biological processes. These findings shed light on which trace elements are important during human brain development and will support studies aimed to unravel the consequences of disrupted metal homeostasis for neurodevelopmental diseases, including those manifested in adulthood.

  20. Assembly of Triblock Amphiphilic Peptides into One-Dimensional Aggregates and Network Formation.

    Science.gov (United States)

    Ozgur, Beytullah; Sayar, Mehmet

    2016-10-06

    Peptide assembly plays a key role in both neurological diseases and development of novel biomaterials with well-defined nanostructures. Synthetic model peptides provide a unique platform to explore the role of intermolecular interactions in the assembly process. A triblock peptide architecture designed by the Hartgerink group is a versatile system which relies on Coulomb interactions, hydrogen bonding, and hydrophobicity to guide these peptides' assembly at three different length scales: β-sheets, double-wall ribbon-like aggregates, and finally a highly porous network structure which can support gels with ≤1% by weight peptide concentration. In this study, by using molecular dynamics simulations of a structure based implicit solvent coarse grained model, we analyzed this hierarchical assembly process. Parametrization of our CG model is based on multiple-state points from atomistic simulations, which enables this model to represent the conformational adaptability of the triblock peptide molecule based on the surrounding medium. Our results indicate that emergence of the double-wall β-sheet packing mechanism, proposed in light of the experimental evidence, strongly depends on the subtle balance of the intermolecular forces. We demonstrate that, even though backbone hydrogen bonding dominates the early nucleation stages, depending on the strength of the hydrophobic and Coulomb forces, alternative structures such as zero-dimensional aggregates with two β-sheets oriented orthogonally (which we refer to as a cross-packed structure) and β-sheets with misoriented hydrophobic side chains are also feasible. We discuss the implications of these competing structures for the three different length scales of assembly by systematically investigating the influence of density, counterion valency, and hydrophobicity.

  1. Beware of Selfies: The Impact of Photo Type on Impression Formation Based on Social Networking Profiles.

    Science.gov (United States)

    Krämer, Nicole C; Feurstein, Markus; Kluck, Jan P; Meier, Yannic; Rother, Marius; Winter, Stephan

    2017-01-01

    Users of social networking sites such as Facebook frequently post self-portraits on their profiles. While research has begun to analyze the motivations for posting such pictures, less is known about how selfies are evaluated by recipients. Although producers of selfies typically aim to create a positive impression, selfies may also be regarded as narcissistic and therefore fail to achieve the intended goal. The aim of this study is to examine the potentially ambivalent reception of selfies compared to photos taken by others based on the Brunswik lens model Brunswik (1956). In a between-subjects online experiment ( N = 297), Facebook profile mockups were shown which differed with regard to picture type (selfie vs. photo taken by others), gender of the profile owner (female vs. male), and number of individuals within a picture (single person vs. group). Results revealed that selfies were indeed evaluated more negatively than photos taken by others. Persons in selfies were rated as less trustworthy, less socially attractive, less open to new experiences, more narcissistic and more extroverted than the same persons in photos taken by others. In addition, gender differences were observed in the perception of pictures. Male profile owners were rated as more narcissistic and less trustworthy than female profile owners, but there was no significant interaction effect of type of picture and gender. Moreover, a mediation analysis of presumed motives for posting selfies revealed that negative evaluations of selfie posting individuals were mainly driven by the perceived motivation of impression management. Findings suggest that selfies are likely to be evaluated less positively than producers of selfies might suppose.

  2. Erythropoietin promotes network formation of transplanted adipose tissue-derived microvascular fragments

    Directory of Open Access Journals (Sweden)

    P Karschnia

    2018-05-01

    Full Text Available The seeding of tissue constructs with adipose tissue-derived microvascular fragments (ad-MVF is an emerging pre-vascularisation strategy. Ad-MVF rapidly reassemble into new microvascular networks after in vivo implantation. Herein it was analysed whether this process was improved by erythropoietin (EPO. Ad-MVF were isolated from green fluorescent protein (GFP+ as well as wild-type C57BL/6 mice and cultivated for 24 h in medium supplemented with EPO (20 IU/mL or vehicle. Freshly isolated, non-cultivated ad-MVF served as controls. Protein expression, cell viability and proliferation of ad-MVF were assessed by proteome profiler array and fluorescence microscopy. GFP+ ad-MVF were seeded on collagen-glycosaminoglycan matrices, which were implanted into dorsal skinfold chambers of C57BL/6 mice, to analyse their vascularisation over 14 d by intravital fluorescence microscopy, histology and immunohistochemistry. Cultivation up-regulated the expression of pro- and anti-angiogenic factors within both vehicle- and EPO-treated ad-MVF when compared with non-cultivated controls. Moreover, EPO treatment suppressed cultivation-associated apoptosis and significantly increased the number of proliferating endothelial cells in ad-MVF when compared with vehicle-treated and non-cultivated ad-MVF. Accordingly, implanted matrices seeded with EPO-treated ad-MVF exhibited an improved vascularisation, as indicated by a significantly higher functional microvessel density. The matrices of the three groups contained a comparably large fraction of GFP+ microvessels originating from the ad-MVF, whereas the tissue surrounding the matrices seeded with EPO-treated ad-MVF exhibited a significantly increased microvessel density when compared with the other two groups. These findings indicated that EPO represents a promising cytokine to further boost the excellent vascularisation properties of ad-MVF in tissue-engineering applications.

  3. Deep multi-scale location-aware 3D convolutional neural networks for automated detection of lacunes of presumed vascular origin

    Directory of Open Access Journals (Sweden)

    Mohsen Ghafoorian

    2017-01-01

    In this paper, we propose an automated two-stage method using deep convolutional neural networks (CNN. We show that this method has good performance and can considerably benefit readers. We first use a fully convolutional neural network to detect initial candidates. In the second step, we employ a 3D CNN as a false positive reduction tool. As the location information is important to the analysis of candidate structures, we further equip the network with contextual information using multi-scale analysis and integration of explicit location features. We trained, validated and tested our networks on a large dataset of 1075 cases obtained from two different studies. Subsequently, we conducted an observer study with four trained observers and compared our method with them using a free-response operating characteristic analysis. Shown on a test set of 111 cases, the resulting CAD system exhibits performance similar to the trained human observers and achieves a sensitivity of 0.974 with 0.13 false positives per slice. A feasibility study also showed that a trained human observer would considerably benefit once aided by the CAD system.

  4. Stem Cells on Biomaterials for Synthetic Grafts to Promote Vascular Healing

    Science.gov (United States)

    Babczyk, Patrick; Conzendorf, Clelia; Klose, Jens; Schulze, Margit; Harre, Kathrin; Tobiasch, Edda

    2014-01-01

    This review is divided into two interconnected parts, namely a biological and a chemical one. The focus of the first part is on the biological background for constructing tissue-engineered vascular grafts to promote vascular healing. Various cell types, such as embryonic, mesenchymal and induced pluripotent stem cells, progenitor cells and endothelial- and smooth muscle cells will be discussed with respect to their specific markers. The in vitro and in vivo models and their potential to treat vascular diseases are also introduced. The chemical part focuses on strategies using either artificial or natural polymers for scaffold fabrication, including decellularized cardiovascular tissue. An overview will be given on scaffold fabrication including conventional methods and nanotechnologies. Special attention is given to 3D network formation via different chemical and physical cross-linking methods. In particular, electron beam treatment is introduced as a method to combine 3D network formation and surface modification. The review includes recently published scientific data and patents which have been registered within the last decade. PMID:26237251

  5. Cardiovascular risk factors and collateral artery formation.

    Science.gov (United States)

    de Groot, D; Pasterkamp, G; Hoefer, I E

    2009-12-01

    Arterial lumen narrowing and vascular occlusion is the actual cause of morbidity and mortality in atherosclerotic disease. Collateral artery formation (arteriogenesis) refers to an active remodelling of non-functional vascular anastomoses to functional collateral arteries, capable to bypass the site of obstruction and preserve the tissue that is jeopardized by ischaemia. Hemodynamic forces such as shear stress and wall stress play a pivotal role in collateral artery formation, accompanied by the expression of various cytokines and invasion of circulating leucocytes. Arteriogenesis hence represents an important compensatory mechanism for atherosclerotic vessel occlusion. As arteriogenesis mostly occurs when lumen narrowing by atherosclerotic plaques takes place, presence of cardiovascular risk factors (e.g. hypertension, hypercholesterolaemia and diabetes) is highly likely. Risk factors for atherosclerotic disease affect collateral artery growth directly and indirectly by altering hemodynamic forces or influencing cellular function and proliferation. Adequate collateralization varies significantly among atherosclerotic patients, some profit from the presence of extensive collateral networks, whereas others do not. Cardiovascular risk factors could increase the risk of adverse cardiovascular events in certain patients because of the reduced protection through an alternative vascular network. Likewise, drugs primarily thought to control cardiovascular risk factors might contribute or counteract collateral artery growth. This review summarizes current knowledge on the influence of cardiovascular risk factors and the effects of cardiovascular medication on the development of collateral vessels in experimental and clinical studies.

  6. Bioprinting of a functional vascularized mouse thyroid gland construct.

    Science.gov (United States)

    Bulanova, Elena A; Koudan, Elizaveta V; Degosserie, Jonathan; Heymans, Charlotte; Pereira, Frederico DAS; Parfenov, Vladislav A; Sun, Yi; Wang, Qi; Akhmedova, Suraya A; Sviridova, Irina K; Sergeeva, Natalia S; Frank, Georgy A; Khesuani, Yusef D; Pierreux, Christophe E; Mironov, Vladimir A

    2017-08-18

    Bioprinting can be defined as additive biofabrication of three-dimensional (3D) tissues and organ constructs using tissue spheroids, capable of self-assembly, as building blocks. The thyroid gland, a relatively simple endocrine organ, is suitable for testing the proposed bioprinting technology. Here we report the bioprinting of a functional vascularized mouse thyroid gland construct from embryonic tissue spheroids as a proof of concept. Based on the self-assembly principle, we generated thyroid tissue starting from thyroid spheroids (TS) and allantoic spheroids (AS) as a source of thyrocytes and endothelial cells (EC), respectively. Inspired by mathematical modeling of spheroid fusion, we used an original 3D bioprinter to print TS in close association with AS within a collagen hydrogel. During the culture, closely placed embryonic tissue spheroids fused into a single integral construct, EC from AS invaded and vascularized TS, and epithelial cells from the TS progressively formed follicles. In this experimental setting, we observed formation of a capillary network around follicular cells, as observed during in utero thyroid development when thyroid epithelium controls the recruitment, invasion and expansion of EC around follicles. To prove that EC from AS are responsible for vascularization of the thyroid gland construct, we depleted endogenous EC from TS before bioprinting. EC from AS completely revascularized depleted thyroid tissue. The cultured bioprinted construct was functional as it could normalize blood thyroxine levels and body temperature after grafting under the kidney capsule of hypothyroid mice. Bioprinting of functional vascularized mouse thyroid gland construct represents a further advance in bioprinting technology, exploring the self-assembling properties of tissue spheroids.

  7. Simposi Internacional "Changing politics through digital networks: the role of ICTs in the formation of new social and political actors and actions"

    Directory of Open Access Journals (Sweden)

    Rosa Borge

    2008-02-01

    Full Text Available

    Participació en el Simposi Internacional "Changing politics through digital networks: the role of ICTs in the formation of new social and political actors and actions", que va tenir lloc a la Universitat de Florència els dies 5 i 6 d'octubre de 2007.

  8. Structural vascular disease in Africans: performance of ethnic-specific waist circumference cut points using logistic regression and neural network analyses: the SABPA study

    OpenAIRE

    Botha, J.; De Ridder, J.H.; Potgieter, J.C.; Steyn, H.S.; Malan, L.

    2013-01-01

    A recently proposed model for waist circumference cut points (RPWC), driven by increased blood pressure, was demonstrated in an African population. We therefore aimed to validate the RPWC by comparing the RPWC and the Joint Statement Consensus (JSC) models via Logistic Regression (LR) and Neural Networks (NN) analyses. Urban African gender groups (N=171) were stratified according to the JSC and RPWC cut point models. Ultrasound carotid intima media thickness (CIMT), blood pressure (BP) and fa...

  9. Constructal vascularized structures

    Science.gov (United States)

    Cetkin, Erdal

    2015-06-01

    Smart features such as self-healing and selfcooling require bathing the entire volume with a coolant or/and healing agent. Bathing the entire volume is an example of point to area (or volume) flows. Point to area flows cover all the distributing and collecting kinds of flows, i.e. inhaling and exhaling, mining, river deltas, energy distribution, distribution of products on the landscape and so on. The flow resistances of a point to area flow can be decreased by changing the design with the guidance of the constructal law, which is the law of the design evolution in time. In this paper, how the flow resistances (heat, fluid and stress) can be decreased by using the constructal law is shown with examples. First, the validity of two assumptions is surveyed: using temperature independent Hess-Murray rule and using constant diameter ducts where the duct discharges fluid along its edge. Then, point to area types of flows are explained by illustrating the results of two examples: fluid networks and heating an area. Last, how the structures should be vascularized for cooling and mechanical strength is documented. This paper shows that flow resistances can be decreased by morphing the shape freely without any restrictions or generic algorithms.

  10. Bioengineering vascularized tissue constructs using an injectable cell-laden enzymatically crosslinked collagen hydrogel derived from dermal extracellular matrix.

    Science.gov (United States)

    Kuo, Kuan-Chih; Lin, Ruei-Zeng; Tien, Han-Wen; Wu, Pei-Yun; Li, Yen-Cheng; Melero-Martin, Juan M; Chen, Ying-Chieh

    2015-11-01

    Tissue engineering promises to restore or replace diseased or damaged tissue by creating functional and transplantable artificial tissues. The development of artificial tissues with large dimensions that exceed the diffusion limitation will require nutrients and oxygen to be delivered via perfusion instead of diffusion alone over a short time period. One approach to perfusion is to vascularize engineered tissues, creating a de novo three-dimensional (3D) microvascular network within the tissue construct. This significantly shortens the time of in vivo anastomosis, perfusion and graft integration with the host. In this study, we aimed to develop injectable allogeneic collagen-phenolic hydroxyl (collagen-Ph) hydrogels that are capable of controlling a wide range of physicochemical properties, including stiffness, water absorption and degradability. We tested whether collagen-Ph hydrogels could support the formation of vascularized engineered tissue graft by human blood-derived endothelial colony-forming cells (ECFCs) and bone marrow-derived mesenchymal stem cells (MSC) in vivo. First, we studied the growth of adherent ECFCs and MSCs on or in the hydrogels. To examine the potential formation of functional vascular networks in vivo, a liquid pre-polymer solution of collagen-Ph containing human ECFCs and MSCs, horseradish peroxidase and hydrogen peroxide was injected into the subcutaneous space or abdominal muscle defect of an immunodeficient mouse before gelation, to form a 3D cell-laden polymerized construct. These results showed that extensive human ECFC-lined vascular networks can be generated within 7 days, the engineered vascular density inside collagen-Ph hydrogel constructs can be manipulated through refinable mechanical properties and proteolytic degradability, and these networks can form functional anastomoses with the existing vasculature to further support the survival of host muscle tissues. Finally, optimized conditions of the cell-laden collagen

  11. Clay-Alcohol-Water Dispersions: Anomalous Viscosity Changes Due to Network Formation of Clay Nanosheets Induced by Alcohol Clustering.

    Science.gov (United States)

    Kimura, Yuji; Haraguchi, Kazutoshi

    2017-05-16

    Clay-alcohol-water ternary dispersions were compared with alcohol-water binary mixtures in terms of viscosity and optical absorbance. Aqueous clay dispersions to which lower alcohols (ethanol, 1-propanol, 2-propanol, and tert-butanol) were added exhibited significant viscosity anomalies (maxima) when the alcohol content was 30-55 wt %, as well as optical absorbance anomalies (maxima). The maximum viscosity (η max ) depended strongly on the clay content and varied between 300 and 8000 mPa·s, making it remarkably high compared with the viscosity anomalies (2 mPa·s) observed in alcohol-water binary mixtures. The alcohol content at η max decreased as the hydrophobicity of the alcohol increased. The ternary dispersions with viscosity anomalies exhibited thixotropic behaviors. The effects of other hydrophilic solvents (glycols) and other kinds of clays were also clarified. Based on these findings and the average particle size changes, the viscosity anomalies in the ternary dispersions were explained by alcohol-clustering-induced network formation of the clay nanosheets. It was estimated that 0.9, 1.7, and 2.5 H 2 O molecules per alcohol molecule were required to stabilize the ethanol, 2-propanol, and tert-butanol, respectively, in the clay-alcohol-water dispersions.

  12. Effects of gintonin on the proliferation, migration, and tube formation of human umbilical-vein endothelial cells: involvement of lysophosphatidic-acid receptors and vascular-endothelial-growth-factor signaling

    Directory of Open Access Journals (Sweden)

    Sung-Hee Hwang

    2016-10-01

    Conclusion: The gintonin-mediated proliferation, migration, and vascular-endothelial-growth-factor release in HUVECs via LPA-receptor activation may be one of in vitro mechanisms underlying ginseng-induced angiogenic and wound-healing effects.

  13. 3D-Printed Biodegradable Polymeric Vascular Grafts.

    Science.gov (United States)

    Melchiorri, A J; Hibino, N; Best, C A; Yi, T; Lee, Y U; Kraynak, C A; Kimerer, L K; Krieger, A; Kim, P; Breuer, C K; Fisher, J P

    2016-02-04

    Congenital heart defect interventions may benefit from the fabrication of patient-specific vascular grafts because of the wide array of anatomies present in children with cardiovascular defects. 3D printing is used to establish a platform for the production of custom vascular grafts, which are biodegradable, mechanically compatible with vascular tissues, and support neotissue formation and growth. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Networking

    OpenAIRE

    Rauno Lindholm, Daniel; Boisen Devantier, Lykke; Nyborg, Karoline Lykke; Høgsbro, Andreas; Fries, de; Skovlund, Louise

    2016-01-01

    The purpose of this project was to examine what influencing factor that has had an impact on the presumed increasement of the use of networking among academics on the labour market and how it is expressed. On the basis of the influence from globalization on the labour market it can be concluded that the globalization has transformed the labour market into a market based on the organization of networks. In this new organization there is a greater emphasis on employees having social qualificati...

  15. Secretory granule formation and membrane recycling by the trans-Golgi network in adipokinetic cells of Locusta migratoria in relation to flight and rest.

    Science.gov (United States)

    Diederen, J H; Vullings, H G

    1995-03-01

    The influence of flight activity on the formation of secretory granules and the concomitant membrane recycling by the trans-Golgi network in the peptidergic neurosecretory adipokinetic cells of Locusta migratoria was investigated by means of ultrastructural morphometric methods. The patterns of labelling of the trans-Golgi network by the exogenous adsorptive endocytotic tracer wheat-germ agglutinin-conjugated horse-radish peroxidase and by the endogenous marker enzyme acid phosphatase were used as parameters and were measured by an automatic image analysis system. The results show that endocytosed fragments of plasma membrane with bound peroxidase label were transported to the trans-Golgi network and used to build new secretory granules. The amounts of peroxidase and especially of acid phosphatase within the trans-Golgi network showed a strong tendency to be smaller in flight-stimulated cells than in non-stimulated cells. The amounts of acid phosphatase in the immature secretory granules originating from the trans-Golgi network were significantly smaller in stimulated cells. The number of immature secretory granules positive for acid phosphatase tended to be higher in stimulated cells. Thus, flight stimulation of adipokinetic cells for 1 h influences the functioning of the trans-Golgi network; this most probably results in a slight enhancement of the production of secretory granules by the trans-Golgi network.

  16. 3D Multiscale Modelling of Angiogenesis and Vascular Tumour Growth

    KAUST Repository

    Perfahl, H.

    2012-11-01

    We present a three-dimensional, multiscale model of vascular tumour growth, which couples nutrient/growth factor transport, blood flow, angiogenesis, vascular remodelling, movement of and interactions between normal and tumour cells, and nutrient-dependent cell cycle dynamics within each cell. We present computational simulations which show how a vascular network may evolve and interact with tumour and healthy cells. We also demonstrate how our model may be combined with experimental data, to predict the spatio-temporal evolution of a vascular tumour.

  17. 3D Multiscale Modelling of Angiogenesis and Vascular Tumour Growth

    KAUST Repository

    Perfahl, H.; Byrne, H. M.; Chen, T.; Estrella, V.; Alarcó n, T.; Lapin, A.; Gatenby, R. A.; Gillies, R. J.; Lloyd, M. C.; Maini, P. K.; Reuss, M.; Owen, M. R.

    2012-01-01

    We present a three-dimensional, multiscale model of vascular tumour growth, which couples nutrient/growth factor transport, blood flow, angiogenesis, vascular remodelling, movement of and interactions between normal and tumour cells, and nutrient-dependent cell cycle dynamics within each cell. We present computational simulations which show how a vascular network may evolve and interact with tumour and healthy cells. We also demonstrate how our model may be combined with experimental data, to predict the spatio-temporal evolution of a vascular tumour.

  18. The development of a reflective vascular training portfolio: Using a ...

    African Journals Online (AJOL)

    ... of formative assessment to certify candidates. Case-based self-reflection in postgraduate training may be used as an additional educational tool and incorporated into the curricula vitae of trainees. We describe the method used to assess a vascular case, based on a self-reflective training method (vascular case portfolio).

  19. Vascular retraction driven by matrix softening

    Science.gov (United States)

    Valentine, Megan

    We recently discovered we can directly apply physical forces and monitor the downstream responses in a living organism in real time through manipulation of the blood vessels of a marine organism called, Botryllus schlosseri. The extracellular matrix (ECM) plays a key role in regulating vascular growth and homeostasis in Botryllus,a basal chordate which has a large, transparent extracorporeal vascular network that can encompass areas >100 cm2. We have determined that lysyl oxidase 1 (LOX1), which is responsible for cross-linking collagen, is expressed in all vascular cells and is critically important for vascular maintenance. Inhibition of LOX1 activity in vivo by the addition of a specific inhibitor, ß-aminopropionitrile (BAPN), caused a rapid, global regression of the entire vascular bed, with some vessels regressing >10 mm within 16 hrs. In this talk, I will discuss the molecular and cellular origins of this systemic remodeling event, which hinges upon the ability of the vascular cells to sense and respond to mechanical signals, while introducing this exciting new model system for studies of biological physics and mechanobiology. Collaborators: Anthony DeTomaso, Delany Rodriguez, Aimal Khankhel (UCSB).

  20. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

    2000-01-01

    The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

  1. Vascular grading of angiogenesis

    DEFF Research Database (Denmark)

    Hansen, S; Grabau, D A; Sørensen, Flemming Brandt

    2000-01-01

    The study aimed to evaluate the prognostic value of angiogenesis by vascular grading of primary breast tumours, and to evaluate the prognostic impact of adding the vascular grade to the Nottingham Prognostic Index (NPI). The investigation included 836 patients. The median follow-up time was 11...... years and 4 months. The microvessels were immunohistochemically stained by antibodies against CD34. Angiogenesis was graded semiquantitatively by subjective scoring into three groups according to the expected number of microvessels in the most vascular tumour area. The vascular grading between observers...... impact for 24% of the patients, who had a shift in prognostic group, as compared to NPI, and implied a better prognostic dissemination. We concluded that the angiogenesis determined by vascular grading has independent prognostic value of clinical relevance for patients with breast cancer....

  2. In vitro evaluation of carbon-nanotube-reinforced bioprintable vascular conduits

    International Nuclear Information System (INIS)

    Dolati, Farzaneh; Yu, Yin; Zhang, Yahui; Ozbolat, Ibrahim T; Jesus, Aribet M De; Sander, Edward A

    2014-01-01

    Vascularization of thick engineered tissue and organ constructs like the heart, liver, pancreas or kidney remains a major challenge in tissue engineering. Vascularization is needed to supply oxygen and nutrients and remove waste in living tissues and organs through a network that should possess high perfusion ability and significant mechanical strength and elasticity. In this paper, we introduce a fabrication process to print vascular conduits directly, where conduits were reinforced with carbon nanotubes (CNTs) to enhance their mechanical properties and bioprintability. In vitro evaluation of printed conduits encapsulated in human coronary artery smooth muscle cells was performed to characterize the effects of CNT reinforcement on the mechanical, perfusion and biological performance of the conduits. Perfusion and permeability, cell viability, extracellular matrix formation and tissue histology were assessed and discussed, and it was concluded that CNT-reinforced vascular conduits provided a foundation for mechanically appealing constructs where CNTs could be replaced with natural protein nanofibers for further integration of these conduits in large-scale tissue fabrication. (paper)

  3. Topology Control Algorithms for Spacecraft Formation Flying Networks Under Connectivity and Time-Delay Constraints, Phase I

    Data.gov (United States)

    National Aeronautics and Space Administration — SSCI is proposing to develop a set of topology control algorithms for a formation flying spacecraft that can be used to design and evaluate candidate formation...

  4. Vascular Access in Children

    International Nuclear Information System (INIS)

    Krishnamurthy, Ganesh; Keller, Marc S.

    2011-01-01

    Establishment of stable vascular access is one of the essential and most challenging procedures in a pediatric hospital. Many clinical specialties provide vascular service in a pediatric hospital. At the top of the “expert procedural pyramid” is the pediatric interventional radiologist, who is best suited and trained to deliver this service. Growing awareness regarding the safety and high success rate of vascular access using image guidance has led to increased demand from clinicians to provide around-the-clock vascular access service by pediatric interventional radiologists. Hence, the success of a vascular access program, with the pediatric interventional radiologist as the key provider, is challenging, and a coordinated multidisciplinary team effort is essential for success. However, there are few dedicated pediatric interventional radiologists across the globe, and also only a couple of training programs exist for pediatric interventions. This article gives an overview of the technical aspects of pediatric vascular access and provides useful tips for obtaining vascular access in children safely and successfully using image guidance.

  5. Pediatric vascular access

    International Nuclear Information System (INIS)

    Donaldson, James S.

    2006-01-01

    Pediatric interventional radiologists are ideally suited to provide vascular access services to children because of inherent safety advantages and higher success from using image-guided techniques. The performance of vascular access procedures has become routine at many adult interventional radiology practices, but this service is not as widely developed at pediatric institutions. Although interventional radiologists at some children's hospitals offer full-service vascular access, there is little or none at others. Developing and maintaining a pediatric vascular access service is a challenge. Interventionalists skilled in performing such procedures are limited at pediatric institutions, and institutional support from clerical staff, nursing staff, and technologists might not be sufficiently available to fulfill the needs of such a service. There must also be a strong commitment by all members of the team to support such a demanding service. There is a slippery slope of expected services that becomes steeper and steeper as the vascular access service grows. This review is intended primarily as general education for pediatric radiologists learning vascular access techniques. Additionally, the pediatric or adult interventional radiologist seeking to expand services might find helpful tips. The article also provides education for the diagnostic radiologist who routinely interprets radiographs containing vascular access devices. (orig.)

  6. Vascular malformations in pediatrics

    International Nuclear Information System (INIS)

    Reith, W.; Shamdeen, M.G.

    2003-01-01

    Vascular malformations are the cause of nearly all non-traumatic intracranial hemorrhage in children beyond the neonatal stage. Therefore, any child presenting with spontaneous intracranial hemorrhage should be evaluated for child abuse and for vascular malformations. Intracerebral malformations of the cerebral vasculature include vein of Galen malformations, arteriovenous malformation (AVM), cavernomas, dural arteriovenous fistulas, venous anomalies (DVA), and capillary teleangiectasies. Although a few familial vascular malformation have been reported, the majority are sporadic. Clinical symptoms, diagnostic and therapeutic options are discussed. (orig.) [de

  7. [Regional geriatric care concept in the District of Lippe : Structural effects and network formation in the case management-based model project].

    Science.gov (United States)

    Şahin, Charlotte; Iseringhausen, Olaf; Hower, Kira; Liebe, Constanze; Rethmeier-Hanke, Anja; Wedmann, Bernd

    2018-04-01

    Regional planning of healthcare requires special consideration for the complex needs of elderly, multimorbid people living in a domestic environment. In the District of Lippe, a hospital (Klinikum Lippe) and network of ambulatory care physicians (Ärztenetz Lippe) developed and tested a geriatric care network based on case management for geriatric patients living in a domestic environment. The establishment of the geriatric care network (e.g. promoting networking acceptance and implementation) was formatively evaluated, e. g. with qualitative methods. Data were acquired by guideline-based interviews with experts and analyzed by qualitative content analysis according to Mayring. Structural effects included forming a cross-sectoral and interdisciplinary network for a functioning care network and a geriatric care pathway. The practical work of case managers (CM) is essential for communication with patients, family members and care providers as well as integrating providers into the network. A critical factor was working together with general practitioners and the close cooperation with the hospital's department of geriatric. The quality of care is improved because of exchange of information between sectors and continuity in the course of care. In the District of Lippe the quality of care was improved and structures of care were integrated by the network according to the needs of the target group. The integrative perspective was achieved in particular by the geriatric care pathway and integration of providers into the communication and care process; however, the scope of this care model could not be extended into routine care due to the rigid and subdivided health care system.

  8. Task-Related Edge Density (TED)-A New Method for Revealing Dynamic Network Formation in fMRI Data of the Human Brain.

    Science.gov (United States)

    Lohmann, Gabriele; Stelzer, Johannes; Zuber, Verena; Buschmann, Tilo; Margulies, Daniel; Bartels, Andreas; Scheffler, Klaus

    2016-01-01

    The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we propose a new method of fMRI data analysis that tackles this problem by considering large-scale, task-related synchronisation networks. Networks consist of nodes and edges connecting them, where nodes correspond to voxels in fMRI data, and the weight of an edge is determined via task-related changes in dynamic synchronisation between their respective times series. Based on these definitions, we developed a new data analysis algorithm that identifies edges that show differing levels of synchrony between two distinct task conditions and that occur in dense packs with similar characteristics. Hence, we call this approach "Task-related Edge Density" (TED). TED proved to be a very strong marker for dynamic network formation that easily lends itself to statistical analysis using large scale statistical inference. A major advantage of TED compared to other methods is that it does not depend on any specific hemodynamic response model, and it also does not require a presegmentation of the data for dimensionality reduction as it can handle large networks consisting of tens of thousands of voxels. We applied TED to fMRI data of a fingertapping and an emotion processing task provided by the Human Connectome Project. TED revealed network-based involvement of a large number of brain areas that evaded detection using traditional GLM-based analysis. We show that our proposed method provides an entirely new window into the immense complexity of human brain function.

  9. Task-Related Edge Density (TED-A New Method for Revealing Dynamic Network Formation in fMRI Data of the Human Brain.

    Directory of Open Access Journals (Sweden)

    Gabriele Lohmann

    Full Text Available The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we propose a new method of fMRI data analysis that tackles this problem by considering large-scale, task-related synchronisation networks. Networks consist of nodes and edges connecting them, where nodes correspond to voxels in fMRI data, and the weight of an edge is determined via task-related changes in dynamic synchronisation between their respective times series. Based on these definitions, we developed a new data analysis algorithm that identifies edges that show differing levels of synchrony between two distinct task conditions and that occur in dense packs with similar characteristics. Hence, we call this approach "Task-related Edge Density" (TED. TED proved to be a very strong marker for dynamic network formation that easily lends itself to statistical analysis using large scale statistical inference. A major advantage of TED compared to other methods is that it does not depend on any specific hemodynamic response model, and it also does not require a presegmentation of the data for dimensionality reduction as it can handle large networks consisting of tens of thousands of voxels. We applied TED to fMRI data of a fingertapping and an emotion processing task provided by the Human Connectome Project. TED revealed network-based involvement of a large number of brain areas that evaded detection using traditional GLM-based analysis. We show that our proposed method provides an entirely new window into the immense complexity of human brain function.

  10. Task-Related Edge Density (TED)—A New Method for Revealing Dynamic Network Formation in fMRI Data of the Human Brain

    Science.gov (United States)

    Lohmann, Gabriele; Stelzer, Johannes; Zuber, Verena; Buschmann, Tilo; Margulies, Daniel; Bartels, Andreas; Scheffler, Klaus

    2016-01-01

    The formation of transient networks in response to external stimuli or as a reflection of internal cognitive processes is a hallmark of human brain function. However, its identification in fMRI data of the human brain is notoriously difficult. Here we propose a new method of fMRI data analysis that tackles this problem by considering large-scale, task-related synchronisation networks. Networks consist of nodes and edges connecting them, where nodes correspond to voxels in fMRI data, and the weight of an edge is determined via task-related changes in dynamic synchronisation between their respective times series. Based on these definitions, we developed a new data analysis algorithm that identifies edges that show differing levels of synchrony between two distinct task conditions and that occur in dense packs with similar characteristics. Hence, we call this approach “Task-related Edge Density” (TED). TED proved to be a very strong marker for dynamic network formation that easily lends itself to statistical analysis using large scale statistical inference. A major advantage of TED compared to other methods is that it does not depend on any specific hemodynamic response model, and it also does not require a presegmentation of the data for dimensionality reduction as it can handle large networks consisting of tens of thousands of voxels. We applied TED to fMRI data of a fingertapping and an emotion processing task provided by the Human Connectome Project. TED revealed network-based involvement of a large number of brain areas that evaded detection using traditional GLM-based analysis. We show that our proposed method provides an entirely new window into the immense complexity of human brain function. PMID:27341204

  11. Unexpected role of the copper transporter ATP7A in PDGF-induced vascular smooth

    Energy Technology Data Exchange (ETDEWEB)

    Ashino, T.; Varadarajan, S.; Urao, N.; Oshikawa, J.; Chen, G. -F.; Wang, H.; Huo, Y.; Finney, L.; Vogt, S.; McKinney, R. D.; Maryon, E. B.; Kaplan, J. H.; Ushio-Fukai, M.; Fukai, T. (Biosciences Division); ( XSD); ( PSC-USR); (Univ. of Illinois at Chicago); (Univ. of Minnesota)

    2010-09-09

    Copper, an essential nutrient, has been implicated in vascular remodeling and atherosclerosis with unknown mechanism. Bioavailability of intracellular copper is regulated not only by the copper importer CTR1 (copper transporter 1) but also by the copper exporter ATP7A (Menkes ATPase), whose function is achieved through copper-dependent translocation from trans-Golgi network (TGN). Platelet-derived growth factor (PDGF) promotes vascular smooth muscle cell (VSMC) migration, a key component of neointimal formation. To determine the role of copper transporter ATP7A in PDGF-induced VSMC migration. Depletion of ATP7A inhibited VSMC migration in response to PDGF or wound scratch in a CTR1/copper-dependent manner. PDGF stimulation promoted ATP7A translocation from the TGN to lipid rafts, which localized at the leading edge, where it colocalized with PDGF receptor and Rac1, in migrating VSMCs. Mechanistically, ATP7A small interfering RNA or CTR small interfering RNA prevented PDGF-induced Rac1 translocation to the leading edge, thereby inhibiting lamellipodia formation. In addition, ATP7A depletion prevented a PDGF-induced decrease in copper level and secretory copper enzyme precursor prolysyl oxidase (Pro-LOX) in lipid raft fraction, as well as PDGF-induced increase in LOX activity. In vivo, ATP7A expression was markedly increased and copper accumulation was observed by synchrotron-based x-ray fluorescence microscopy at neointimal VSMCs in wire injury model. These findings suggest that ATP7A plays an important role in copper-dependent PDGF-stimulated VSMC migration via recruiting Rac1 to lipid rafts at the leading edge, as well as regulating LOX activity. This may contribute to neointimal formation after vascular injury. Our findings provide insight into ATP7A as a novel therapeutic target for vascular remodeling and atherosclerosis.

  12. A synergistic approach to the design, fabrication and evaluation of 3D printed micro and nano featured scaffolds for vascularized bone tissue repair

    International Nuclear Information System (INIS)

    Holmes, Benjamin; Bulusu, Kartik; Plesniak, Michael; Zhang, Lijie Grace

    2016-01-01

    3D bioprinting has begun to show great promise in advancing the development of functional tissue/organ replacements. However, to realize the true potential of 3D bioprinted tissues for clinical use requires the fabrication of an interconnected and effective vascular network. Solving this challenge is critical, as human tissue relies on an adequate network of blood vessels to transport oxygen, nutrients, other chemicals, biological factors and waste, in and out of the tissue. Here, we have successfully designed and printed a series of novel 3D bone scaffolds with both bone formation supporting structures and highly interconnected 3D microvascular mimicking channels, for efficient and enhanced osteogenic bone regeneration as well as vascular cell growth. Using a chemical functionalization process, we have conjugated our samples with nano hydroxyapatite (nHA), for the creation of novel micro and nano featured devices for vascularized bone growth. We evaluated our scaffolds with mechanical testing, hydrodynamic measurements and in vitro human mesenchymal stem cell (hMSC) adhesion (4 h), proliferation (1, 3 and 5 d) and osteogenic differentiation (1, 2 and 3 weeks). These tests confirmed bone-like physical properties and vascular-like flow profiles, as well as demonstrated enhanced hMSC adhesion, proliferation and osteogenic differentiation. Additional in vitro experiments with human umbilical vein endothelial cells also demonstrated improved vascular cell growth, migration and organization on micro-nano featured scaffolds. (paper)

  13. A synergistic approach to the design, fabrication and evaluation of 3D printed micro and nano featured scaffolds for vascularized bone tissue repair

    Science.gov (United States)

    Holmes, Benjamin; Bulusu, Kartik; Plesniak, Michael; Zhang, Lijie Grace

    2016-02-01

    3D bioprinting has begun to show great promise in advancing the development of functional tissue/organ replacements. However, to realize the true potential of 3D bioprinted tissues for clinical use requires the fabrication of an interconnected and effective vascular network. Solving this challenge is critical, as human tissue relies on an adequate network of blood vessels to transport oxygen, nutrients, other chemicals, biological factors and waste, in and out of the tissue. Here, we have successfully designed and printed a series of novel 3D bone scaffolds with both bone formation supporting structures and highly interconnected 3D microvascular mimicking channels, for efficient and enhanced osteogenic bone regeneration as well as vascular cell growth. Using a chemical functionalization process, we have conjugated our samples with nano hydroxyapatite (nHA), for the creation of novel micro and nano featured devices for vascularized bone growth. We evaluated our scaffolds with mechanical testing, hydrodynamic measurements and in vitro human mesenchymal stem cell (hMSC) adhesion (4 h), proliferation (1, 3 and 5 d) and osteogenic differentiation (1, 2 and 3 weeks). These tests confirmed bone-like physical properties and vascular-like flow profiles, as well as demonstrated enhanced hMSC adhesion, proliferation and osteogenic differentiation. Additional in vitro experiments with human umbilical vein endothelial cells also demonstrated improved vascular cell growth, migration and organization on micro-nano featured scaffolds.

  14. Engineering the mechanical and biological properties of nanofibrous vascular grafts for in situ vascular tissue engineering.

    Science.gov (United States)

    Henry, Jeffrey J D; Yu, Jian; Wang, Aijun; Lee, Randall; Fang, Jun; Li, Song

    2017-08-17

    Synthetic small diameter vascular grafts have a high failure rate, and endothelialization is critical for preventing thrombosis and graft occlusion. A promising approach is in situ tissue engineering, whereby an acellular scaffold is implanted and provides stimulatory cues to guide the in situ remodeling into a functional blood vessel. An ideal scaffold should have sufficient binding sites for biomolecule immobilization and a mechanical property similar to native tissue. Here we developed a novel method to blend low molecular weight (LMW) elastic polymer during electrospinning process to increase conjugation sites and to improve the mechanical property of vascular grafts. LMW elastic polymer improved the elasticity of the scaffolds, and significantly increased the amount of heparin conjugated to the micro/nanofibrous scaffolds, which in turn increased the loading capacity of vascular endothelial growth factor (VEGF) and prolonged the release of VEGF. Vascular grafts were implanted into the carotid artery of rats to evaluate the in vivo performance. VEGF treatment significantly enhanced endothelium formation and the overall patency of vascular grafts. Heparin coating also increased cell infiltration into the electrospun grafts, thus increasing the production of collagen and elastin within the graft wall. This work demonstrates that LMW elastic polymer blending is an approach to engineer the mechanical and biological property of micro/nanofibrous vascular grafts for in situ vascular tissue engineering.

  15. Uterine Vascular Lesions

    Science.gov (United States)

    Vijayakumar, Abhishek; Srinivas, Amruthashree; Chandrashekar, Babitha Moogali; Vijayakumar, Avinash

    2013-01-01

    Vascular lesions of the uterus are rare; most reported in the literature are arteriovenous malformations (AVMs). Uterine AVMs can be congenital or acquired. In recent years, there has been an increasing number of reports of acquired vascular lesions of the uterus following pregnancy, abortion, cesarean delivery, and curettage. It can be seen from these reports that there is confusion concerning the terminology of uterine vascular lesions. There is also a lack of diagnostic criteria and management guidelines, which has led to an increased number of unnecessary invasive procedures (eg, angiography, uterine artery embolization, hysterectomy for abnormal vaginal bleeding). This article familiarizes readers with various vascular lesions of the uterus and their management. PMID:24340126

  16. Magnetic resonance vascular imaging

    International Nuclear Information System (INIS)

    Axel, L

    1989-01-01

    The basis principles of MRI are reviewed in order to understand how blood flow effects arise in conventional imaging. Then some of the ways these effects have ben used in MRI techniques specifically designed for vascular imaging, are considered. (author)

  17. Sustained Angiopoietin-2 Expression Disrupts Vessel Formation and Inhibits Glioma Growth

    Directory of Open Access Journals (Sweden)

    Ok-Hee Lee

    2006-05-01

    Full Text Available Systematic analyses of the expression of angiogenic regulators in cancer models should yield useful information for the development of novel therapies for malignant gliomas. In this study, we analyzed tumor growth, vascularization, and angiopoietin-2 (Ang2 expression during the development of U-87 MG xenografts. We found that tumoral angiogenesis in this model follows a multistage process characterized by avascular, prolific peripheral angiogenesis, and late vascular phases. On day 4, we observed an area of central necrosis, a peripheral ring of Ang2-positive glioma cells, and reactive Ang2-positive vascular structures in the tumor/brain interface. When the tumor had developed a vascular network, Ang2 was expressed only in peripheral vascular structures. Because Ang2 expression was downmodulated in the late stages of development, probably to maintain a stable tumoral vasculature, we next studied whether sustained Ang2 expression might impair vascular development and, ultimately, tumor growth. Ang2 prevented the formation of capillary-like structures and impaired angiogenesis in a chorioallantoic membrane chicken model. Finally, we tested the effect of sustained Ang2 expression on U-87 MG xenograff development. Ang2 significantly prolonged the survival of intracranial U-87 MG tumor-bearing animals. Examination of Ang2treated xenograffs revealed areas of tumor necrosis and vascular damage. We therefore conclude that deregulated Ang2 expression during gliomagenesis hindered successful angiogenesis and that therapies that sustain Ang2 expression might be effective against malignant gliomas.

  18. Formation and Control of Sulfur Oxides in Sour Gas Oxy-Combustion: Prediction Using a Reactor Network Model

    KAUST Repository

    Bongartz, Dominik

    2015-11-19

    © 2015 American Chemical Society. Sour natural gas currently requires expensive gas cleanup before it can be used in power generation because it contains large amounts of hydrogen sulfide (H2S) and carbon dioxide (CO2) that entail a low heating value and highly corrosive combustion products. A potential alternative is to use the gas directly in a gas turbine process employing oxy-fuel combustion, which could eliminate the need for gas cleanup while also enabling the application of carbon capture and sequestration, possibly combined with enhanced oil recovery (EOR). However, the exact influence of an oxy-fuel environment on the combustion products of sour gas has not been quantified yet. In this work, we used a reactor network model for the combustor and the gas turbine together with our recently assembled and validated detailed chemical reaction mechanism for sour gas combustion to investigate the influence of some basic design parameters on the combustion products of natural gas and sour gas in CO2 or H2O diluted oxy-fuel combustion as well as in conventional air combustion. Our calculations show that oxy-fuel combustion produces up to 2 orders of magnitude less of the highly corrosive product sulfur trioxide (SO3) than air combustion, which clearly demonstrates its potential in handling sulfur containing fuels. Unlike in air combustion, in oxy-fuel combustion, SO3 is mainly formed in the flame zone of the combustor and is then consumed as the combustion products are cooled in the dilution zone of the combustor and the turbine. In oxy-fuel combustion, H2O dilution leads to a higher combustion efficiency than CO2 dilution. However, if the process is to be combined with EOR, CO2 dilution makes it easier to comply with the very low levels of oxygen (O2) required in the EOR stream. Our calculations also show that it might even be beneficial to operate slightly fuel-rich because this simultaneously decreases the O2 and SO3 concentration further. The flame zone

  19. Retinal vascular segmentation using superpixel-based line operator and its application to vascular topology estimation.

    Science.gov (United States)

    Na, Tong; Xie, Jianyang; Zhao, Yitian; Zhao, Yifan; Liu, Yue; Wang, Yongtian; Liu, Jiang

    2018-05-09

    Automatic methods of analyzing of retinal vascular networks, such as retinal blood vessel detection, vascular network topology estimation, and arteries/veins classification are of great assistance to the ophthalmologist in terms of diagnosis and treatment of a wide spectrum of diseases. We propose a new framework for precisely segmenting retinal vasculatures, constructing retinal vascular network topology, and separating the arteries and veins. A nonlocal total variation inspired Retinex model is employed to remove the image intensity inhomogeneities and relatively poor contrast. For better generalizability and segmentation performance, a superpixel-based line operator is proposed as to distinguish between lines and the edges, thus allowing more tolerance in the position of the respective contours. The concept of dominant sets clustering is adopted to estimate retinal vessel topology and classify the vessel network into arteries and veins. The proposed segmentation method yields competitive results on three public data sets (STARE, DRIVE, and IOSTAR), and it has superior performance when compared with unsupervised segmentation methods, with accuracy of 0.954, 0.957, and 0.964, respectively. The topology estimation approach has been applied to five public databases (DRIVE,STARE, INSPIRE, IOSTAR, and VICAVR) and achieved high accuracy of 0.830, 0.910, 0.915, 0.928, and 0.889, respectively. The accuracies of arteries/veins classification based on the estimated vascular topology on three public databases (INSPIRE, DRIVE and VICAVR) are 0.90.9, 0.910, and 0.907, respectively. The experimental results show that the proposed framework has effectively addressed crossover problem, a bottleneck issue in segmentation and vascular topology reconstruction. The vascular topology information significantly improves the accuracy on arteries/veins classification. © 2018 American Association of Physicists in Medicine.

  20. Using the D-Wave 2X Quantum Computer to Explore the Formation of Global Terrorist Networks

    Energy Technology Data Exchange (ETDEWEB)

    Ambrosiano, John Joseph [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Roberts, Randy Mark [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Sims, Benjamin Hayden [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-05-15

    Social networks with signed edges (+/-) play an important role in an area of social network theory called structural balance. In these networks, edges represent relationships that are labeled as either friendly (+) or hostile (-). A signed social network is balanced only if all cycles of three or more nodes in the graph have an odd number of hostile edges. A fundamental property of a balanced network is that it can be cleanly divided into 2 factions, where all relationships within each faction are friendly, and all relationships between members of different factions are hostile. The more unbalanced a network is, the more edges will fail to adhere to this rule, making factions more ambiguous. Social theory suggests unbalanced networks should be unstable, a finding that has been supported by research on gangs, which shows that unbalanced relationships are associated with greater violence, possibly due to this increased ambiguity about factional allegiances (Nakamura et al). One way to estimate the imbalance in a network, if only edge relationships are known, is to assign nodes to factions that minimize the number of violations of the edge rule described above. This problem is known to be computationally NP-hard. However, Facchetti et al. have pointed out that it is equivalent to an Ising model with a Hamiltonian that effectively counts the number of edge rule violations. Therefore, finding the assignment of factions that minimizes energy of the equivalent Ising system yields an estimate of the imbalance in the network. Based on the Ising model equivalence of the signed-social network balance problem, we have used the D-Wave 2X quantum annealing computer to explore some aspects of signed social networks. Because connectivity in the D-Wave computer is limited to its particular native topology, arbitrary networks cannot be represented directly. Rather, they must be “embedded” using a technique in which multiple qubits are chained together with special weights to

  1. Convergent evolution of vascular optimization in kelp (Laminariales).

    Science.gov (United States)

    Drobnitch, Sarah Tepler; Jensen, Kaare H; Prentice, Paige; Pittermann, Jarmila

    2015-10-07

    Terrestrial plants and mammals, although separated by a great evolutionary distance, have each arrived at a highly conserved body plan in which universal allometric scaling relationships govern the anatomy of vascular networks and key functional metabolic traits. The universality of allometric scaling suggests that these phyla have each evolved an 'optimal' transport strategy that has been overwhelmingly adopted by extant species. To truly evaluate the dominance and universality of vascular optimization, however, it is critical to examine other, lesser-known, vascularized phyla. The brown algae (Phaeophyceae) are one such group--as distantly related to plants as mammals, they have convergently evolved a plant-like body plan and a specialized phloem-like transport network. To evaluate possible scaling and optimization in the kelp vascular system, we developed a model of optimized transport anatomy and tested it with measurements of the giant kelp, Macrocystis pyrifera, which is among the largest and most successful of macroalgae. We also evaluated three classical allometric relationships pertaining to plant vascular tissues with a diverse sampling of kelp species. Macrocystis pyrifera displays strong scaling relationships between all tested vascular parameters and agrees with our model; other species within the Laminariales display weak or inconsistent vascular allometries. The lack of universal scaling in the kelps and the presence of optimized transport anatomy in M. pyrifera raises important questions about the evolution of optimization and the possible competitive advantage conferred by optimized vascular systems to multicellular phyla. © 2015 The Author(s).

  2. A contribution from dielectric analysis to the study of the formation of multi-wall carbon nanotubes percolated networks in epoxy resin under an electric field

    International Nuclear Information System (INIS)

    Risi, Celso L.S.; Hattenhauer, Irineu; Ramos, Airton; Coelho, Luiz A.F.; Pezzin, Sérgio H.

    2015-01-01

    The formation of percolation networks in epoxy matrix nanocomposites reinforced with multi-wall carbon nanotubes (MWNT) during the curing process, at different MWNT contents, was studied by using a parallel plate cell subjected to a 300 V/cm AC electric field at 1 kHz. The percolation was verified by the electrical current output measured during and after the resin curing. The behavior of electric dipoles was characterized by impedance spectroscopy and followed the Debye first order dispersion model, by which an average relaxation time of 6.0 × 10 −4 s and a cut-off frequency of 1.7 kHz were experimentally found. By applying the theory of percolation, a critical probability, p c , equal to 0.038 vol% and an exponent of conductivity of 2.0 were found. Both aligned and random samples showed dipole relaxation times typical of interfacial and/or charge-hopping polarization, while the permittivity exhibited an exponential decrease with frequency. This behavior can be related to the increased ability to trap electrical charges due to the formation of the carbon nanotubes network. Optical and electron microscopies confirm the theoretical prediction that the application of an electric field during cure helps the process of MWNT debundling in epoxy resin. - Highlights: • We report the formation of percolating networks of MWNTs under AC electric field. • MWNT/epoxy dielectric properties were measured by impedance spectroscopy. • Lower percolation thresholds were obtained for composites with aligned CNTs. • Application of AC electric field helps the debundling of CNTs. • CNT/Epoxy with percolated networks presents interfacial and hopping polarizations

  3. Improved vascularization of planar membrane diffusion devices following continuous infusion of vascular endothelial growth factor.

    Science.gov (United States)

    Trivedi, N; Steil, G M; Colton, C K; Bonner-Weir, S; Weir, G C

    2000-01-01

    Improving blood vessel formation around an immunobarrier device should improve the survival of the encapsulated tissue. In the present study we investigated the formation of new blood vessels around a planar membrane diffusion device (the Baxter Theracyte System) undergoing a continuous infusion of vascular endothelial growth factor through the membranes and into the surrounding tissue. Each device (20 microl) had both an inner immunoisolation membrane and an outer vascularizing membrane. Human recombinant vascular endothelial growth factor-165 was infused at 100 ng/day (low dose: n = 6) and 500 ng/day (high dose: n = 7) for 10 days into devices implanted s.c. in Sprague-Dawley rats; noninfused devices transplanted for an identical period were used as controls (n = 5). Two days following the termination of VEGF infusion, devices were loaded with 20 microl of Lispro insulin (1 U/kg) and the kinetics of insulin release from the lumen of the device was assessed. Devices were then explanted and the number of blood vessels (capillary and noncapillary) was quantified using morphometry. High-dose vascular endothelial growth factor infusion resulted in two- to threefold more blood vessels around the device than that obtained with the noninfused devices and devices infused with low-dose vascular endothelial growth factor. This increase in the number of blood vessels was accompanied by a modest increase in insulin diffusion from the device in the high-dose vascular endothelial growth factor infusion group. We conclude that vascular endothelial growth factor can be used to improve blood vessel formation adjacent to planar membrane diffusion devices.

  4. Sticky or Slippery Wetting: Network Formation Conditions Can Provide a One-Way Street for Water Flow on Platinum-cured Silicone.

    Science.gov (United States)

    Wang, Chenyu; Nair, Sithara S; Veeravalli, Sharon; Moseh, Patricia; Wynne, Kenneth J

    2016-06-08

    In the course of studies on Sylgard 184 (S-PDMS), we discovered strong effects on receding contact angles (CAs), θrec, while cure conditions have little effect on advancing CAs. Network formation at high temperatures resulted in high θadv of 115-120° and high θrec ≥ 80°. After network formation at low temperatures (≤25 °C), θadv was still high but θrec was 30-50°. Uncertainty about compositional effects on wetting behavior resulted in similar experiments with a model D(V)D(H) silicone elastomer (Pt-PDMS) composed of a vinyl-terminated poly(dimethylsiloxane) (PDMS) base and a polymeric hydromethylsilane cross-linker. Again, network formation at high temperature (∼100 °C) resulted in high CAs, while low-temperature curing retained high advancing CAs but gave low receding CAs (θrec 30-50°). These changes in receding CAs translate to strong effects on water adhesion, wp, which is the actual work required to separate a liquid (water) from a surface: wp ∝ (1 + θrec). When the values θrec 84° for high-temperature and θrec 50° for low-temperature network formation are used, wp is ∼1.5 times higher for curing at low temperature. The origin of low receding contact angles was investigated by attenuated total reflectance IR spectroscopy. Absorptions for Si-OH hydrogen-bonded to water (3350 cm(-1)) were stronger for low- versus high-temperature curing. This result is attributed to faster hydrosilylation during curing at higher temperatures that consumes Si-H before autoxidation to Si-OH. Sharp bands at 3750 and 3690 cm(-1) due to isolated -Si-OH are more prominent for Pt-PDMS than those for S-PDMS, which may be due to an effect of functionalized nanofiller. To explore the impact of wp on water droplet flow, gradient coatings of S-PDMS and Pt-PDMS elastomers were prepared by coating a slide, maintaining opposite ends at high and low temperatures and thus forming a thermal gradient. When the slide was tilted, a droplet moved easily on the high

  5. Molecular parallels between neural and vascular development.

    Science.gov (United States)

    Eichmann, Anne; Thomas, Jean-Léon

    2013-01-01

    The human central nervous system (CNS) features a network of ~400 miles of blood vessels that receives >20% of the body's cardiac output and uses most of its blood glucose. Many human diseases, including stroke, retinopathy, and cancer, are associated with the biology of CNS blood vessels. These vessels originate from extrinsic cell populations, including endothelial cells and pericytes that colonize the CNS and interact with glia and neurons to establish the blood-brain barrier and control cerebrovascular exchanges. Neurovascular interactions also play important roles in adult neurogenic niches, which harbor a unique population of neural stem cells that are intimately associated with blood vessels. We here review the cellular and molecular mechanisms required to establish the CNS vascular network, with a special focus on neurovascular interactions and the functions of vascular endothelial growth factors.

  6. The vascular basement membrane in the healthy and pathological brain.

    Science.gov (United States)

    Thomsen, Maj S; Routhe, Lisa J; Moos, Torben

    2017-10-01

    The vascular basement membrane contributes to the integrity of the blood-brain barrier (BBB), which is formed by brain capillary endothelial cells (BCECs). The BCECs receive support from pericytes embedded in the vascular basement membrane and from astrocyte endfeet. The vascular basement membrane forms a three-dimensional protein network predominantly composed of laminin, collagen IV, nidogen, and heparan sulfate proteoglycans that mutually support interactions between BCECs, pericytes, and astrocytes. Major changes in the molecular composition of the vascular basement membrane are observed in acute and chronic neuropathological settings. In the present review, we cover the significance of the vascular basement membrane in the healthy and pathological brain. In stroke, loss of BBB integrity is accompanied by upregulation of proteolytic enzymes and degradation of vascular basement membrane proteins. There is yet no causal relationship between expression or activity of matrix proteases and the degradation of vascular matrix proteins in vivo. In Alzheimer's disease, changes in the vascular basement membrane include accumulation of Aβ, composite changes, and thickening. The physical properties of the vascular basement membrane carry the potential of obstructing drug delivery to the brain, e.g. thickening of the basement membrane can affect drug delivery to the brain, especially the delivery of nanoparticles.

  7. Formation of contractile networks and fibers in the medial cell cortex through myosin-II turnover, contraction, and stress-stabilization.

    Science.gov (United States)

    Nie, Wei; Wei, Ming-Tzo; Ou-Yang, H Daniel; Jedlicka, Sabrina S; Vavylonis, Dimitrios

    2015-01-01

    The morphology of adhered cells depends crucially on the formation of a contractile meshwork of parallel and cross-linked fibers along the contacting surface. The motor activity and minifilament assembly of non-muscle myosin-II is an important component of cortical cytoskeletal remodeling during mechanosensing. We used experiments and computational modeling to study cortical myosin-II dynamics in adhered cells. Confocal microscopy was used to image the medial cell cortex of HeLa cells stably expressing myosin regulatory light chain tagged with GFP (MRLC-GFP). The distribution of MRLC-GFP fibers and focal adhesions was classified into three types of network morphologies. Time-lapse movies show: myosin foci appearance and disappearance; aligning and contraction; stabilization upon alignment. Addition of blebbistatin, which perturbs myosin motor activity, leads to a reorganization of the cortical networks and to a reduction of contractile motions. We quantified the kinetics of contraction, disassembly and reassembly of myosin networks using spatio-temporal image correlation spectroscopy (STICS). Coarse-grained numerical simulations include bipolar minifilaments that contract and align through specified interactions as basic elements. After assuming that minifilament turnover decreases with increasing contractile stress, the simulations reproduce stress-dependent fiber formation in between focal adhesions above a threshold myosin concentration. The STICS correlation function in simulations matches the function measured in experiments. This study provides a framework to help interpret how different cortical myosin remodeling kinetics may contribute to different cell shape and rigidity depending on substrate stiffness. © 2015 Wiley Periodicals, Inc.

  8. Distributed Joint Cluster Formation and Resource Allocation Scheme for Cooperative Data Collection in Virtual MIMO-Based M2M Networks

    Directory of Open Access Journals (Sweden)

    Xi Luan

    2015-01-01

    Full Text Available An efficient data collection scheme plays an important role for the real-time intelligent monitoring in many machine-to-machine (M2M networks. In this paper, a distributed joint cluster formation and resource allocation scheme for data collection in cluster-based M2M networks is proposed. Specifically, in order to utilize the advantages of cooperation, we first propose a hierarchical transmission model which contains two communication phases. In the first phase, the intracluster information sharing is carried out by all the nodes within the same cluster. Then these nodes transmit the total information to the BS cooperatively with virtual-MIMO (VMIMO protocol in the second phase. To grasp the properties and advantages of this cooperative transmission strategy, the theoretical analysis results are provided. The key issue in this system is to form the clusters and allocate resources efficiently. Since the optimization problem on this issue is an NP-hard problem, a feasible joint scheme for the cluster formation and resource allocation is proposed in this paper, which is carried out via coalition formation game with a distributed algorithm. This scheme can reduce the complexity while keeping an attractive performance. Simulation results show the properties of the proposed scheme and its advantages when comparing with the noncooperative scheme for the data collection in a practical scenario.

  9. In vivo endothelization of tubular vascular grafts through in situ recruitment of endothelial and endothelial progenitor cells by RGD-fused mussel adhesive proteins

    International Nuclear Information System (INIS)

    Kang, Tae-Yun; Lee, Jung Ho; Kang, Jo-A; Rhie, Jong-Won; Kim, Bum Jin; Cha, Hyung Joon; Hong, Jung Min; Kim, Byoung Soo; Cho, Dong-Woo

    2015-01-01

    The use of tissue mimics in vivo, including patterned vascular networks, is expected to facilitate the regeneration of functional tissues and organs with large volumes. Maintaining patency of channels in contact with blood is an important issue in the development of a functional vascular network. Endothelium is the only known completely non-thrombogenic material; however, results from treatments to induce endothelialization are inconclusive. The present study was designed to evaluate the clinical applicability of in situ recruitment of endothelial cells/endothelial progenitor cells (EC/EPC) and pre-endothelization using a recombinant mussel adhesive protein fused with arginine–glycine–aspartic acid peptide (MAP-RGD) coating in a model of vascular graft implantation. Microporous polycaprolactone (PCL) scaffolds were fabricated with salt leaching methods and their surfaces were modified with collagen and MAP-RGD. We then evaluated their anti-thrombogenicity with an in vitro hemocompatibility assessment and a 4-week implantation in the rabbit carotid artery. We observed that MAP-RGD coating reduced the possibility of early in vivo graft failure and enhanced re-endothelization by in situ recruitment of EC/EPC (patency rate: 2/3), while endothelization prior to implantation aggravated the formation of thrombosis and/or IH (patency rate: 0/3). The results demonstrated that in situ recruitment of EC/EPC by MAP-RGD could be a promising strategy for vascular applications. In addition, it rules out several issues associated with pre-endothelization, such as cell source, purity, functional modulation and contamination. Further evaluation of long term performance and angiogenesis from the luminal surface may lead to the clinical use of MAP-RGD for tubular vascular grafts and regeneration of large-volume tissues with functional vascular networks. (paper)

  10. Aggregation and network formation in self-assembly of protein (H3.1) by a coarse-grained Monte Carlo simulation

    Science.gov (United States)

    Pandey, R. B.; Farmer, B. L.

    2014-11-01

    Multi-scale aggregation to network formation of interacting proteins (H3.1) are examined by a knowledge-based coarse-grained Monte Carlo simulation as a function of temperature and the number of protein chains, i.e., the concentration of the protein. Self-assembly of corresponding homo-polymers of constitutive residues (Cys, Thr, and Glu) with extreme residue-residue interactions, i.e., attractive (Cys-Cys), neutral (Thr-Thr), and repulsive (Glu-Glu), are also studied for comparison with the native protein. Visual inspections show contrast and similarity in morphological evolutions of protein assembly, aggregation of small aggregates to a ramified network from low to high temperature with the aggregation of a Cys-polymer, and an entangled network of Glu and Thr polymers. Variations in mobility profiles of residues with the concentration of the protein suggest that the segmental characteristic of proteins is altered considerably by the self-assembly from that in its isolated state. The global motion of proteins and Cys polymer chains is enhanced by their interacting network at the low temperature where isolated chains remain quasi-static. Transition from globular to random coil transition, evidenced by the sharp variation in the radius of gyration, of an isolated protein is smeared due to self-assembly of interacting networks of many proteins. Scaling of the structure factor S(q) with the wave vector q provides estimates of effective dimension D of the mass distribution at multiple length scales in self-assembly. Crossover from solid aggregates (D ˜ 3) at low temperature to a ramified fibrous network (D ˜ 2) at high temperature is observed for the protein H3.1 and Cys polymers in contrast to little changes in mass distribution (D ˜ 1.6) of fibrous Glu- and Thr-chain configurations.

  11. Overview of vascular disease

    International Nuclear Information System (INIS)

    Bisset, G.S. III

    1998-01-01

    Vascular disease in the pediatric population is a poorly understood process which is often underestimated in its incidence. The common beginnings of such ubiquitous diseases as atherosclerosis manifest themselves at a cellular level shortly after birth. Other common systemic disorders, including congestive heart failure and sepsis, are also intricately associated with dysfunctional vasculature. Progress in the understanding of normal and pathophysiologic processes within the vascular system begins with the 'control center' - the endothelial cell. The purpose of this review is to consolidate a body of knowledge on the processes that occur at the cellular level within the blood vessel wall, and to simplify the understanding of how imbalances in these physiologic parameters result in vascular disease. (orig.)

  12. Study of pattern formation in multilayer adaptive network of phase oscillators in application to brain dynamics analysis

    Science.gov (United States)

    Kirsanov, Daniil V.; Nedaivozov, Vladimir O.; Makarov, Vladimir V.; Goremyko, Mikhail V.; Hramov, Alexander E.

    2017-04-01

    In the report we study the mechanisms of phase synchronization in the model of adaptive network of Kuramoto phase oscillators and discuss the possibility of the further application of the obtained results for the analysis of the neural network of brain. In our theoretical study the model network represents itself as the multilayer structure, in which the links between the elements belonging to the different layers are arranged according to the competitive rule. In order to analyze the dynamical states of the multilayer network we calculate and compare the values of local and global order parameter, which describe the degree of coherence between the neighboring nodes and the elements over whole network, respectively. We find that the global synchronous dynamics takes place for the large values of the coupling strength and are characterized by the identical topology of the interacting layers and a homogeneous distribution of the link strength within each layer. We also show that the partial (or cluster) synchronization, occurs for the small values of the coupling strength, lead to the emergence of the scale-free topology, within the layers.

  13. Topology Control Algorithms for Spacecraft Formation Flying Networks Under Connectivity and Time-Delay Constraints, Phase II

    Data.gov (United States)

    National Aeronautics and Space Administration — SSCI is proposing to develop, test and deliver a set of topology control algorithms and software for a formation flying spacecraft that can be used to design and...

  14. Impact of Bounded Noise and Rewiring on the Formation and Instability of Spiral Waves in a Small-World Network of Hodgkin-Huxley Neurons.

    Science.gov (United States)

    Yao, Yuangen; Deng, Haiyou; Ma, Chengzhang; Yi, Ming; Ma, Jun

    2017-01-01

    Spiral waves are observed in the chemical, physical and biological systems, and the emergence of spiral waves in cardiac tissue is linked to some diseases such as heart ventricular fibrillation and epilepsy; thus it has importance in theoretical studies and potential medical applications. Noise is inevitable in neuronal systems and can change the electrical activities of neuron in different ways. Many previous theoretical studies about the impacts of noise on spiral waves focus an unbounded Gaussian noise and even colored noise. In this paper, the impacts of bounded noise and rewiring of network on the formation and instability of spiral waves are discussed in small-world (SW) network of Hodgkin-Huxley (HH) neurons through numerical simulations, and possible statistical analysis will be carried out. Firstly, we present SW network of HH neurons subjected to bounded noise. Then, it is numerically demonstrated that bounded noise with proper intensity σ, amplitude A, or frequency f can facilitate the formation of spiral waves when rewiring probability p is below certain thresholds. In other words, bounded noise-induced resonant behavior can occur in the SW network of neurons. In addition, rewiring probability p always impairs spiral waves, while spiral waves are confirmed to be robust for small p, thus shortcut-induced phase transition of spiral wave with the increase of p is induced. Furthermore, statistical factors of synchronization are calculated to discern the phase transition of spatial pattern, and it is confirmed that larger factor of synchronization is approached with increasing of rewiring probability p, and the stability of spiral wave is destroyed.

  15. Intensification of Development of Mixed Transportation of Freight in Ukraine through Formation of the Network of Transportation and Logistic Centres and Transportation and Logistic Clusters

    Directory of Open Access Journals (Sweden)

    Karpenko Oksana O.

    2013-11-01

    Full Text Available Development of mixed transportation is a prospective direction of development of the transportation system of Ukraine. The article analyses the modern state of development of mixed transportation of freight in Ukraine. The most popular types of combined transportation (refers to multi-modal are container and contrailer trains, which are formed both in Ukraine (Viking and Yaroslav and in other countries, first of all, Belarus (Zubr. One of the reasons of underdevelopment of mixed transportation of freight in Ukraine is absence of a developed network of transportation and logistic centres. The article offers to form a network of transportation and logistic centres in Ukraine as a way of intensification of development of mixed transportations of freight, since they facilitate co-ordination of use of various types of transport and support integrated management of material flows. Transportation and logistic centres should become a start-up complex, around which transportation and logistic clusters would be gradually formed. Transportation and logistic clusters is a new efficient form of network organisation and management of transportation and logistic services and they also ensure growth of efficiency of use of the regional transportation and logistic potential of Ukraine. The article shows prospective supporting transportation and logistic centres and centres of formation of transportation and logistic clusters in the territory of Ukraine. Formation of efficient transportation and logistic system of Ukraine on the basis of a network of transportation and logistic clusters would facilitate entering of Ukraine into the world transportation environment and would allow acceleration of introduction of efficient logistic schemes of freight delivery, in particular, mixed transportation of freight.

  16. Analysis on the Content, Features and Formation of Motivation on Strategic Network%企业战略网络内涵、特征及形成动因分析

    Institute of Scientific and Technical Information of China (English)

    刘宇; 张敬文; 阮平南

    2011-01-01

    在梳理战略网络理论相关研究的基础上,对战略网络内涵和特征进行重新界定,并对战略网络形成动因进行深入研究.%Based on the research of strategic network theory, this paper re - defines the content and characteristics of strategic network. At last, it studies the causes for the formation of strategic network.

  17. ECOLOGICAL BASES OF FORMATION OF THE LAND USE OF THE TERRITORIES OF THE NATURAL RESERVOIR FUND IN THE COMPOSITION OF ECOLOGICAL NETWORK OF UKRAINE

    Directory of Open Access Journals (Sweden)

    Hetmanchik I.

    2017-11-01

    Full Text Available The article highlights ecological and economic measures on the formation of land use territories of the nature reserve fund within the ecological network of Ukraine, its current state and problems, as well as directions of improvement. These measures are directed towards the balanced provision of the needs of the population and sectors of the economy with land resources, rational use and protection of lands, preservation of landscape and biodiversity, creation of environmentally safe living conditions of the population and economic activity and protection of land from depletion, degradation and pollution.

  18. KEY ISSUES OF CONCEPTS' FORMATION OF THE NETWORK OF RESOURCE CENTER OF DISTANCE EDUCATION OF GENERAL EDUCATION INSTITUTIONS

    Directory of Open Access Journals (Sweden)

    Yuriy M. Bogachkov

    2013-06-01

    Full Text Available In the article the problem of constructing a network of resource centers for Distance Education to meet the needs of general secondary schools is presented. Modern educational trends in the use of Internet services in education are viewed.  Main contradictions, solution of which helps to create a network of resource centers, are identified. The definition of key terms related to the range of issues are given. The basic categories of participants, who  implementation of e-learning and networking are oriented on. There are considered the basic tasks of  distance education resource centers' functioning and types of supporting: personnel, regulatory, informative, systematic and  technical etc. The review of possible models of implementation of  students' distance education is reviewed . Three options for business models of resource centers, depending on funding  sources are offered.

  19. Neuronal sFlt1 and Vegfaa determine venous sprouting and spinal cord vascularization

    DEFF Research Database (Denmark)

    Wild, Raphael; Klems, Alina; Takamiya, Masanari

    2017-01-01

    Formation of organ-specific vasculatures requires cross-talk between developing tissue and specialized endothelial cells. Here we show how developing zebrafish spinal cord neurons coordinate vessel growth through balancing of neuron-derived Vegfaa, with neuronal sFlt1 restricting Vegfaa......-Kdrl mediated angiogenesis at the neurovascular interface. Neuron-specific loss of flt1 or increased neuronal vegfaa expression promotes angiogenesis and peri-neural tube vascular network formation. Combining loss of neuronal flt1 with gain of vegfaa promotes sprout invasion into the neural tube. On loss...... of neuronal flt1, ectopic sprouts emanate from veins involving special angiogenic cell behaviours including nuclear positioning and a molecular signature distinct from primary arterial or secondary venous sprouting. Manipulation of arteriovenous identity or Notch signalling established that ectopic sprouting...

  20. Endothelial microparticles: Sophisticated vesicles modulating vascular function

    Science.gov (United States)

    Curtis, Anne M; Edelberg, Jay; Jonas, Rebecca; Rogers, Wade T; Moore, Jonni S; Syed, Wajihuddin; Mohler, Emile R

    2015-01-01

    Endothelial microparticles (EMPs) belong to a family of extracellular vesicles that are dynamic, mobile, biological effectors capable of mediating vascular physiology and function. The release of EMPs can impart autocrine and paracrine effects on target cells through surface interaction, cellular fusion, and, possibly, the delivery of intra-vesicular cargo. A greater understanding of the formation, composition, and function of EMPs will broaden our understanding of endothelial communication and may expose new pathways amenable for therapeutic manipulation. PMID:23892447

  1. Synthesis of PVA Hydrogel for Prosthetic Discus Nucleus Pulposus: Formation of Interpenetrating Polymer Network (IPN) PVA Hydrogel by Gamma Rays

    International Nuclear Information System (INIS)

    Darwis, Darmawan; Erizal; Lely Hardiningsih; Razzak, Mirzan T.

    2004-01-01

    Research on synthesis of IPN PVA hydrogel for using as prosthetic discus nucleus has been carried out. Base hydrogel network (network I) was made by reacting the solution of polyvinyl alcohol (PVA) 10 - 15 % w/w with formaldehyde at 80 o C for several hours. Hydrogel network II (as IPN network) was then made by immersion of base hydrogel into polymer solution (PVP or PVA) until hydrogel swell to equilibrium volume. The hydrogel then irradiated using gamma rays at various doses. The results show that IPN PVA-PVP and IPN PVA-PVP hydrogels have higher compression strength compared to base hydrogel. IPN PVA-PVA hydrogel made by irradiating base hydrogel (immersed into polymer solution) with 25, 50 and 100 kGy have compression strength at 5 mm displacement 2.72; 2.83; and 3.25 kg/cm 2 respectively, While base hydrogel has compression strength of 1.75 kg/cm 2 . IPN PVA-PVP and PVA-PVA hydrogels made by irradiating base hydrogel with 100 kGy still retain high water content i.e. 72 and 74 % respectively. Beside that they show good re-absorption property after compression treatment that is hydrogel can return to the original shape after compressed to 12 mm displacement (80% of initial height on hydrogel) at relatively short time, less than 15 minutes. (author)

  2. Them That's Got: How Tie Formation in Partnership Networks Gives High Schools Differential Access to Social Capital

    Science.gov (United States)

    Bridwell-Mitchell, E. N.

    2017-01-01

    School partnerships are important sources of school social capital. Schools may have unequal access to social capital due to the pattern of relationships in the school-partner network. Using data on school resource needs, sociometric measures, and a set of multilevel logit models, the results of a study of 211 New York City public high schools and…

  3. Renal posttransplant's vascular complications

    Directory of Open Access Journals (Sweden)

    Bašić Dragoslav

    2003-01-01

    Full Text Available INTRODUCTION Despite high graft and recipient survival figures worldwide today, a variety of technical complications can threaten the transplant in the postoperative period. Vascular complications are commonly related to technical problems in establishing vascular continuity or to damage that occurs during donor nephrectomy or preservation [13]. AIM The aim of the presenting study is to evaluate counts and rates of vascular complications after renal transplantation and to compare the outcome by donor type. MATERIAL AND METHODS A total of 463 kidneys (319 from living related donor LD and 144 from cadaveric donor - CD were transplanted during the period between June 1975 and December 1998 at the Urology & Nephrology Institute of Clinical Centre of Serbia in Belgrade. Average recipients' age was 33.7 years (15-54 in LD group and 39.8 (19-62 in CD group. Retrospectively, we analyzed medical records of all recipients. Statistical analysis is estimated using Hi-squared test and Fischer's test of exact probability. RESULTS Major vascular complications including vascular anastomosis thrombosis, internal iliac artery stenosis, internal iliac artery rupture obliterant vasculitis and external iliac vein rupture were analyzed. In 25 recipients (5.4% some of major vascular complications were detected. Among these cases, 22 of them were from CD group vs. three from LD group. Relative rate of these complications was higher in CD group vs. LD group (p<0.0001. Among these complications dominant one was vascular anastomosis thrombosis which occurred in 18 recipients (17 from CD vs. one from LD. Of these recipients 16 from CD lost the graft, while the rest of two (one from each group had lethal outcome. DISCUSSION Thrombosis of renal allograft vascular anastomosis site is the most severe complication following renal transplantation. In the literature, renal allograft thrombosis is reported with different incidence rates, from 0.5-4% [14, 15, 16]. Data from the

  4. Endothelial Dll4 overexpression reduces vascular response and inhibits tumor growth and metastasization in vivo.

    Science.gov (United States)

    Trindade, Alexandre; Djokovic, Dusan; Gigante, Joana; Mendonça, Liliana; Duarte, António

    2017-03-14

    The inhibition of Delta-like 4 (Dll4)/Notch signaling has been shown to result in excessive, nonfunctional vessel proliferation and significant tumor growth suppression. However, safety concerns emerged with the identification of side effects resulting from chronic Dll4/Notch blockade. Alternatively, we explored the endothelial Dll4 overexpression using different mouse tumor models. We used a transgenic mouse model of endothelial-specific Dll4 overexpression, previously produced. Growth kinetics and vascular histopathology of several types of solid tumors was evaluated, namely Lewis Lung Carcinoma xenografts, chemically-induced skin papillomas and RIP1-Tag2 insulinomas. We found that increased Dll4/Notch signaling reduces tumor growth by reducing vascular endothelial growth factor (VEGF)-induced endothelial proliferation, tumor vessel density and overall tumor blood supply. In addition, Dll4 overexpression consistently improved tumor vascular maturation and functionality, as indicated by increased vessel calibers, enhanced mural cell recruitment and increased network perfusion. Importantly, the tumor vessel normalization is not more effective than restricted vessel proliferation, but was found to prevent metastasis formation and allow for increased delivery to the tumor of concomitant chemotherapy, improving its efficacy. By reducing endothelial sensitivity to VEGF, these results imply that Dll4/Notch stimulation in tumor microenvironment could be beneficial to solid cancer patient treatment by reducing primary tumor size, improving tumor drug delivery and reducing metastization. Endothelial specific Dll4 overexpression thus appears as a promising anti-angiogenic modality that might improve cancer control.

  5. Augmentation of radiation response with the vascular targeting agent ZD6126

    International Nuclear Information System (INIS)

    Hoang Tien; Huang Shyhmin; Armstrong, Eric; Eickhoff, Jens C.; Harari, Paul M.

    2006-01-01

    Purpose: To examine the antivascular and antitumor activity of the vascular targeting agent ZD6126 in combination with radiation in lung and head-and-neck (H and N) cancer models. The overall hypothesis was that simultaneous targeting of tumor cells (radiation) and tumor vasculature (ZD6126) might enhance tumor cell killing. Methods and Materials: A series of in vitro studies using human umbilical vein endothelial cells (HUVEC) and in vivo studies in athymic mice bearing human lung (H226) and H and N (squamous cell carcinoma [SCC]1, SCC6) tumor xenografts treated with ZD6126 and/or radiation were performed. Results: ZD6126 inhibited the capillary-like network formation in HUVEC. Treatment of HUVEC with ZD6126 resulted in cell cycle arrest in G2/M, with decrease of cells in S phase and proliferation inhibition in a dose-dependent manner. ZD6126 augmented the cell-killing effect of radiation and radiation-induced apoptosis in HUVEC. The combination of ZD6126 and radiation further decreased tumor vascularization in an in vivo Matrigel angiogenesis assay. In tumor xenografts, ZD6126 enhanced the antitumor activity of radiation, resulting in tumor growth delay. Conclusions: These preclinical studies suggest that ZD6126 can augment the radiation response of proliferating endothelial H and N and lung cancer cells. These results complement recent reports suggesting the potential value of combining radiation with vascular targeting/antiangiogenic agents

  6. A first vascularized skin equivalent as an alternative to animal experimentation.

    Science.gov (United States)

    Groeber, Florian; Engelhardt, Lisa; Lange, Julia; Kurdyn, Szymon; Schmid, Freia F; Rücker, Christoph; Mielke, Stephan; Walles, Heike; Hansmann, Jan

    2016-01-01

    Tissue-engineered skin equivalents mimic key aspects of the human skin, and can thus be employed as wound coverage for large skin defects or as in vitro test systems as an alternative to animal models. However, current skin equivalents lack a functional vasculature limiting clinical and research applications. This study demonstrates the generation of a vascularized skin equivalent with a perfused vascular network by combining a biological vascularized scaffold (BioVaSc) based on a decellularized segment of a porcine jejunum and a tailored bioreactor system. Briefly, the BioVaSc was seeded with human fibroblasts, keratinocytes, and human microvascular endothelial cells. After 14 days at the air-liquid interface, hematoxylin & eosin and immunohistological staining revealed a specific histological architecture representative of the human dermis and epidermis including a papillary-like architecture at the dermal-epidermal-junction. The formation of the skin barrier was measured non-destructively using impedance spectroscopy. Additionally, endothelial cells lined the walls of the formed vessels that could be perfused with a physiological volume flow. Due to the presence of a complex in-vivo-like vasculature, the here shown skin equivalent has the potential for skin grafting and represents a sophisticated in vitro model for dermatological research.

  7. Reconfigurable Digital Coherent Receiver for Metro-Access Networks Supporting Mixed Modulation Formats and Bit-rates

    DEFF Research Database (Denmark)

    Caballero Jambrina, Antonio; Guerrero Gonzalez, Neil; Arlunno, Valeria

    2013-01-01

    A single, reconfigurable, digital coherent receiver is proposed and experimentally demonstrated for converged wireless and optical fiber transport. The capacity of reconstructing the full transmitted optical field allows for the demodulation of mixed modulation formats and bit-rates. We performed...

  8. Software for hyperspectral, joint photographic experts group (.JPG), portable network graphics (.PNG) and tagged image file format (.TIFF) segmentation

    Science.gov (United States)

    Bruno, L. S.; Rodrigo, B. P.; Lucio, A. de C. Jorge

    2016-10-01

    This paper presents a system developed by an application of a neural network Multilayer Perceptron for drone acquired agricultural image segmentation. This application allows a supervised user training the classes that will posteriorly be interpreted by neural network. These classes will be generated manually with pre-selected attributes in the application. After the attribute selection a segmentation process is made to allow the relevant information extraction for different types of images, RGB or Hyperspectral. The application allows extracting the geographical coordinates from the image metadata, geo referencing all pixels on the image. In spite of excessive memory consume on hyperspectral images regions of interest, is possible to perform segmentation, using bands chosen by user that can be combined in different ways to obtain different results.

  9. How the shape of an H-bonded network controls proton-coupled water activation in HONO formation.

    Science.gov (United States)

    Relph, Rachael A; Guasco, Timothy L; Elliott, Ben M; Kamrath, Michael Z; McCoy, Anne B; Steele, Ryan P; Schofield, Daniel P; Jordan, Kenneth D; Viggiano, Albert A; Ferguson, Eldon E; Johnson, Mark A

    2010-01-15

    Many chemical reactions in atmospheric aerosols and bulk aqueous environments are influenced by the surrounding solvation shell, but the precise molecular interactions underlying such effects have rarely been elucidated. We exploited recent advances in isomer-specific cluster vibrational spectroscopy to explore the fundamental relation between the hydrogen (H)-bonding arrangement of a set of ion-solvating water molecules and the chemical activity of this ensemble. We find that the extent to which the nitrosonium ion (NO+)and water form nitrous acid (HONO) and a hydrated proton cluster in the critical trihydrate depends sensitively on the geometrical arrangement of the water molecules in the network. Theoretical analysis of these data details the role of the water network in promoting charge delocalization.

  10. iTRAQ-Based Proteomic Analysis Reveals Potential Regulation Networks of IBA-Induced Adventitious Root Formation in Apple

    Directory of Open Access Journals (Sweden)

    Chao Lei

    2018-02-01

    Full Text Available Adventitious root (AR formation, which is controlled by endogenous and environmental factors, is indispensable for vegetative asexual propagation. However, comprehensive proteomic data on AR formation are still lacking. The aim of this work was to study indole-3-butyric acid (IBA-induced AR formation in the dwarf apple rootstock ‘T337’. In this study, the effect of IBA on AR formation was analysed. Subsequent to treatment with IBA, both the rooting rate and root length of ‘T337’ increased significantly. An assessment of hormone levels in basal stem cuttings suggested that auxin, abscisic acid, and brassinolide were higher in basal stem cuttings that received the exogenous IBA application; while zeatin riboside, gibberellins, and jasmonic acid were lower than non-treated basal stem cuttings. To explore the underlying molecular mechanism, an isobaric tags for relative and absolute quantification (iTRAQ-based proteomic technique was employed to identify the expression profiles of proteins at a key period of adventitious root induction (three days after IBA treatment. In total, 3355 differentially expressed proteins (DEPs were identified. Many DEPs were closely related to carbohydrate metabolism and energy production, protein homeostasis, reactive oxygen and nitric oxide signaling, and cell wall remodeling biological processes; as well as the phytohormone signaling, which was the most critical process in response to IBA treatment. Further, RT-qPCR analysis was used to evaluate the expression level of nine genes that are involved in phytohormone signaling and their transcriptional levels were mostly in accordance with the protein patterns. Finally, a putative work model was proposed. Our study establishes a foundation for further research and sheds light on IBA-mediated AR formation in apple as well as other fruit rootstock cuttings.

  11. Extensin network formation in Vitis vinifera callus cells is an essential and causal event in rapid and H2O2-induced reduction in primary cell wall hydration

    Science.gov (United States)

    2011-01-01

    Background Extensin deposition is considered important for the correct assembly and biophysical properties of primary cell walls, with consequences to plant resistance to pathogens, tissue morphology, cell adhesion and extension growth. However, evidence for a direct and causal role for the extensin network formation in changes to cell wall properties has been lacking. Results Hydrogen peroxide treatment of grapevine (Vitis vinifera cv. Touriga) callus cell walls was seen to induce a marked reduction in their hydration and thickness. An analysis of matrix proteins demonstrated this occurs with the insolubilisation of an abundant protein, GvP1, which displays a primary structure and post-translational modifications typical of dicotyledon extensins. The hydration of callus cell walls free from saline-soluble proteins did not change in response to H2O2, but fully regained this capacity after addition of extensin-rich saline extracts. To assay the specific contribution of GvP1 cross-linking and other wall matrix proteins to the reduction in hydration, GvP1 levels in cell walls were manipulated in vitro by binding selected fractions of extracellular proteins and their effect on wall hydration during H2O2 incubation assayed. Conclusions This approach allowed us to conclude that a peroxidase-mediated formation of a covalently linked network of GvP1 is essential and causal in the reduction of grapevine callus wall hydration in response to H2O2. Importantly, this approach also indicated that extensin network effects on hydration was only partially irreversible and remained sensitive to changes in matrix charge. We discuss this mechanism and the importance of these changes to primary wall properties in the light of extensin distribution in dicotyledons. PMID:21672244

  12. Vascular Complications of Pancreatitis: Role of Interventional Therapy

    Energy Technology Data Exchange (ETDEWEB)

    Barge, Jaideep U.; Lopera, Jorge E. [University of Texas Health Science Center, San Antonio (United States)

    2012-02-15

    Major vascular complications related to pancreatitis can cause life-threatening hemorrhage and have to be dealt with as an emergency, utilizing a multidisciplinary approach of angiography, endoscopy or surgery. These may occur secondary to direct vascular injuries, which result in the formation of splanchnic pseudoaneurysms, gastrointestinal etiologies such as peptic ulcer disease and gastroesophageal varices, and post-operative bleeding related to pancreatic surgery. In this review article, we discuss the pathophysiologic mechanisms, diagnostic modalities, and treatment of pancreatic vascular complications, with a focus on the role of minimally-invasive interventional therapies such as angioembolization, endovascular stenting, and ultrasound-guided percutaneous thrombin injection in their management.

  13. The transcriptional regulatory network of Corynebacterium jeikeium K411 and its interaction with metabolic routes contributing to human body odor formation.

    Science.gov (United States)

    Barzantny, Helena; Schröder, Jasmin; Strotmeier, Jasmin; Fredrich, Eugenie; Brune, Iris; Tauch, Andreas

    2012-06-15

    Lipophilic corynebacteria are involved in the generation of volatile odorous products in the process of human body odor formation by degrading skin lipids and specific odor precursors. Therefore, these bacteria represent appropriate model systems for the cosmetic industry to examine axillary malodor formation on the molecular level. To understand the transcriptional control of metabolic pathways involved in this process, the transcriptional regulatory network of the lipophilic axilla isolate Corynebacterium jeikeium K411 was reconstructed from the complete genome sequence. This bioinformatic approach detected a gene-regulatory repertoire of 83 candidate proteins, including 56 DNA-binding transcriptional regulators, nine two-component systems, nine sigma factors, and nine regulators with diverse physiological functions. Furthermore, a cross-genome comparison among selected corynebacterial species of the taxonomic cluster 3 revealed a common gene-regulatory repertoire of 44 transcriptional regulators, including the MarR-like regulator Jk0257, which is exclusively encoded in the genomes of this taxonomical subline. The current network reconstruction comprises 48 transcriptional regulators and 674 gene-regulatory interactions that were assigned to five interconnected functional modules. Most genes involved in lipid degradation are under the combined control of the global cAMP-sensing transcriptional regulator GlxR and the LuxR-family regulator RamA, probably reflecting the essential role of lipid degradation in C. jeikeium. This study provides the first genome-scale in silico analysis of the transcriptional regulation of metabolism in a lipophilic bacterium involved in the formation of human body odor. Copyright © 2012 Elsevier B.V. All rights reserved.

  14. Vinpocetine Attenuates the Osteoblastic Differentiation of Vascular Smooth Muscle Cells.

    Directory of Open Access Journals (Sweden)

    Yun-Yun Ma

    Full Text Available Vascular calcification is an active process of osteoblastic differentiation of vascular smooth muscle cells; however, its definite mechanism remains unknown. Vinpocetine, a derivative of the alkaloid vincamine, has been demonstrated to inhibit the high glucose-induced proliferation of vascular smooth muscle cells; however, it remains unknown whether vinpocetine can affect the osteoblastic differentiation of vascular smooth muscle cells. We hereby investigated the effect of vinpocetine on vascular calcification using a beta-glycerophosphate-induced cell model. Our results showed that vinpocetine significantly reduced the osteoblast-like phenotypes of vascular smooth muscle cells including ALP activity, osteocalcin, collagen type I, Runx2 and BMP-2 expression as well as the formation of mineralized nodule. Vinpocetine, binding to translocation protein, induced phosphorylation of extracellular signal-related kinase and Akt and thus inhibited the translocation of nuclear factor-kappa B into the nucleus. Silencing of translocator protein significantly attenuated the inhibitory effect of vinpocetine on osteoblastic differentiation of vascular smooth muscle cells. Taken together, vinpocetine may be a promising candidate for the clinical therapy of vascular calcification.

  15. Major Vascular Neurocognitive Disorder: A Reappraisal to Vascular Dementia

    Directory of Open Access Journals (Sweden)

    Emre Kumral

    2017-03-01

    Full Text Available Major vascular neurocognitive disorder (NCD is the second leading form of dementia after Alzheimer’s disease, accounting for 17-20% of all dementias. Vascular NCD is a progressive disease caused by reduced cerebral blood flow related to multiple large volume or lacunar infarcts that induce a sudden onset and stepwise decline in cognitive abilities. Despite its prevalence and clinical importance, there is still controversy in the terminology of vascular NCD. Only after the release of Diagnostic and Statistical Manual of Mental Disorders-5 (DSM-5 (2013 did the American Psychiatric Association define vascular dementia as “major vascular NCD”. This review includes an overview of risk factors, pathophysiology, types, diagnostic and clinical features of major vascular NCD, and current treatment options of vascular NCD regarding to DSM-5 criteria

  16. Plant Vascular Biology 2010

    Energy Technology Data Exchange (ETDEWEB)

    Ding, Biao

    2014-11-17

    This grant supported the Second International Conference on Plant Vascular Biology (PVB 2010) held July 24-28, 2010 on the campus of Ohio State University, Columbus, Ohio. Biao Ding (Ohio State University; OSU) and David Hannapel (Iowa State University; ISU) served as co-chairs of this conference. Biao Ding served as the local organizer. PVB is defined broadly here to include studies on the biogenesis, structure and function of transport systems in plants, under conditions of normal plant growth and development as well as of plant interactions with pathogens. The transport systems cover broadly the xylem, phloem, plasmodesmata and vascular cell membranes. The PVB concept has emerged in recent years to emphasize the integrative nature of the transport systems and approaches to investigate them.

  17. Vascular cognitive impairment

    Directory of Open Access Journals (Sweden)

    N.V. Vakhnina

    2014-01-01

    Full Text Available Vascular pathology of the brain is the second most common cause of cognitive impairment after Alzheimer's disease. The article describes the modern concepts of etiology, pathogenetic mechanisms, clinical features and approaches to diagnosis and therapy of vascular cognitive impairment (VCI. Cerebrovascular accident, chronic cerebral circulatory insufficiency and their combination, sometimes in combination with a concomitant neurodegenerative process, are shown to be the major types of brain lesions leading to VCI. The clinical presentation of VCI is characterized by the neuropsychological status dominated by impairment of the executive frontal functions (planning, control, attention in combination with focal neurological symptoms. The diagnosis is based on comparing of the revealed neuropsychological and neurological features with neuroimaging data. Neurometabolic, acetylcholinergic, glutamatergic, and other vasoactive drugs and non-pharmacological methods are widely used to treat VCI. 

  18. Vascular Surgery and Robotics

    Directory of Open Access Journals (Sweden)

    Indrani Sen

    2016-01-01

    Full Text Available The application of robotics to Vascular surgery has not progressed as rapidly as of endovascular technology, but this is changing with the amalgamation of these two fields. The advent of Endovascular robotics is an exciting field which overcomes many of the limitations of endovascular therapy like vessel tortuosity and operator fatigue. This has much clinical appeal for the surgeon and hold significant promise of better patient outcomes. As with most newer technological advances, it is still limited by cost and availability. However, this field has seen some rapid progress in the last decade with the technology moving into the clinical realm. This review details the development of robotics, applications, outcomes, advantages, disadvantages and current advances focussing on Vascular and Endovascular robotics

  19. Direct activation of EXPANSIN14 by LBD18 in the gene regulatory network of lateral root formation in Arabidopsis

    OpenAIRE

    Kim, Jungmook; Lee, Han Woo

    2013-01-01

    Root system architecture is important for plants to adapt to a changing environment. The major determinant of the root system is lateral roots originating from the primary root. The developmental process of lateral root formation can be divided into priming, initiation, primordium development and the emergence of lateral roots, and is well characterized in Arabidopsis. The hormone auxin plays a critical role in lateral root development, and several auxin response modules involving AUXIN RESPO...

  20. Evolution‐development congruence in pattern formation dynamics: Bifurcations in gene expression and regulation of networks structures

    Science.gov (United States)

    Kohsokabe, Takahiro

    2016-01-01

    ABSTRACT Search for possible relationships between phylogeny and ontogeny is important in evolutionary‐developmental biology. Here we uncover such relationships by numerical evolution and unveil their origin in terms of dynamical systems theory. By representing developmental dynamics of spatially located cells with gene expression dynamics with cell‐to‐cell interaction under external morphogen gradient, gene regulation networks are evolved under mutation and selection with the fitness to approach a prescribed spatial pattern of expressed genes. For most numerical evolution experiments, evolution of pattern over generations and development of pattern by an evolved network exhibit remarkable congruence. Both in the evolution and development pattern changes consist of several epochs where stripes are formed in a short time, while for other temporal regimes, pattern hardly changes. In evolution, these quasi‐stationary regimes are generations needed to hit relevant mutations, while in development, they are due to some gene expression that varies slowly and controls the pattern change. The morphogenesis is regulated by combinations of feedback or feedforward regulations, where the upstream feedforward network reads the external morphogen gradient, and generates a pattern used as a boundary condition for the later patterns. The ordering from up to downstream is common in evolution and development, while the successive epochal changes in development and evolution are represented as common bifurcations in dynamical‐systems theory, which lead to the evolution‐development congruence. Mechanism of exceptional violation of the congruence is also unveiled. Our results provide a new look on developmental stages, punctuated equilibrium, developmental bottlenecks, and evolutionary acquisition of novelty in morphogenesis. J. Exp. Zool. (Mol. Dev. Evol.) 326B:61–84, 2016. © 2015 The Authors. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution

  1. Evolution-development congruence in pattern formation dynamics: Bifurcations in gene expression and regulation of networks structures.

    Science.gov (United States)

    Kohsokabe, Takahiro; Kaneko, Kunihiko

    2016-01-01

    Search for possible relationships between phylogeny and ontogeny is important in evolutionary-developmental biology. Here we uncover such relationships by numerical evolution and unveil their origin in terms of dynamical systems theory. By representing developmental dynamics of spatially located cells with gene expression dynamics with cell-to-cell interaction under external morphogen gradient, gene regulation networks are evolved under mutation and selection with the fitness to approach a prescribed spatial pattern of expressed genes. For most numerical evolution experiments, evolution of pattern over generations and development of pattern by an evolved network exhibit remarkable congruence. Both in the evolution and development pattern changes consist of several epochs where stripes are formed in a short time, while for other temporal regimes, pattern hardly changes. In evolution, these quasi-stationary regimes are generations needed to hit relevant mutations, while in development, they are due to some gene expression that varies slowly and controls the pattern change. The morphogenesis is regulated by combinations of feedback or feedforward regulations, where the upstream feedforward network reads the external morphogen gradient, and generates a pattern used as a boundary condition for the later patterns. The ordering from up to downstream is common in evolution and development, while the successive epochal changes in development and evolution are represented as common bifurcations in dynamical-systems theory, which lead to the evolution-development congruence. Mechanism of exceptional violation of the congruence is also unveiled. Our results provide a new look on developmental stages, punctuated equilibrium, developmental bottlenecks, and evolutionary acquisition of novelty in morphogenesis. © 2015 The Authors. Journal of Experimental Zoology Part B: Molecular and Developmental Evolution Published by Wiley Periodicals, Inc.

  2. Vascular lesions following radiation

    International Nuclear Information System (INIS)

    Fajardo, L.F.; Berthrong, M.

    1988-01-01

    The special radiation sensitivity of the vascular system is mainly linked to that of endothelial cells, which are perhaps the most radiation-vulnerable elements of mesenchymal tissues. Within the vascular tree, radiation injures most often capillaries, sinusoids, and small arteries, in that order. Lesions of veins are observed less often, but in certain tissues the veins are regularly damaged (e.g., intestine) or are the most affected structures (i.e., liver). Large arteries do suffer the least; however, when significant damage does occur in an elastic artery (e.g., thrombosis or rupture), it tends to be clinically significant and even fatal. Although not always demonstrable in human tissues, radiation vasculopathy generally is dose and time dependent. Like other radiation-induced lesions, the morphology in the vessels is not specific, but it is characteristic enough to be often recognizable. Vascular injury, especially by therapeutic radiation is not just a morphologic marker. It is a mediator of tissue damage; perhaps the most consistent pathogenetic mechanism in delayed radiation injury

  3. Pulmonary vascular imaging

    International Nuclear Information System (INIS)

    Fedullo, P.F.; Shure, D.

    1987-01-01

    A wide range of pulmonary vascular imaging techniques are available for the diagnostic evaluation of patients with suspected pulmonary vascular disease. The characteristics of any ideal technique would include high sensitivity and specificity, safety, simplicity, and sequential applicability. To date, no single technique meets these ideal characteristics. Conventional pulmonary angiography remains the gold standard for the diagnosis of acute thromboembolic disease despite the introduction of newer techniques such as digital subtraction angiography and magnetic resonance imaging. Improved noninvasive lower extremity venous testing methods, particularly impedance plethysmography, and ventilation-perfusion scanning can play significant roles in the noninvasive diagnosis of acute pulmonary emboli when properly applied. Ventilation-perfusion scanning may also be useful as a screening test to differentiate possible primary pulmonary hypertension from chronic thromboembolic pulmonary hypertension. And, finally, angioscopy may be a useful adjunctive technique to detect chronic thromboembolic disease and determine operability. Optimal clinical decision-making, however, will continue to require the proper interpretation of adjunctive information obtained from the less-invasive techniques, applied with an understanding of the natural history of the various forms of pulmonary vascular disease and with a knowledge of the capabilities and shortcomings of the individual techniques

  4. Hydrogels with precisely controlled integrin activation dictate vascular patterning and permeability

    Science.gov (United States)

    Li, Shuoran; Nih, Lina R.; Bachman, Haylee; Fei, Peng; Li, Yilei; Nam, Eunwoo; Dimatteo, Robert; Carmichael, S. Thomas; Barker, Thomas H.; Segura, Tatiana

    2017-09-01

    Integrin binding to bioengineered hydrogel scaffolds is essential for tissue regrowth and regeneration, yet not all integrin binding can lead to tissue repair. Here, we show that through engineering hydrogel materials to promote α3/α5β1 integrin binding, we can promote the formation of a space-filling and mature vasculature compared with hydrogel materials that promote αvβ3 integrin binding. In vitro, α3/α5β1 scaffolds promoted endothelial cells to sprout and branch, forming organized extensive networks that eventually reached and anastomosed with neighbouring branches. In vivo, α3/α5β1 scaffolds delivering vascular endothelial growth factor (VEGF) promoted non-tortuous blood vessel formation and non-leaky blood vessels by 10 days post-stroke. In contrast, materials that promote αvβ3 integrin binding promoted endothelial sprout clumping in vitro and leaky vessels in vivo. This work shows that precisely controlled integrin activation from a biomaterial can be harnessed to direct therapeutic vessel regeneration and reduce VEGF-induced vascular permeability in vivo.

  5. Differentiation and Application of Induced Pluripotent Stem Cell-Derived Vascular Smooth Muscle Cells.

    Science.gov (United States)

    Maguire, Eithne Margaret; Xiao, Qingzhong; Xu, Qingbo

    2017-11-01

    Vascular smooth muscle cells (VSMCs) play a role in the development of vascular disease, for example, neointimal formation, arterial aneurysm, and Marfan syndrome caused by genetic mutations in VSMCs, but little is known about the mechanisms of the disease process. Advances in induced pluripotent stem cell technology have now made it possible to derive VSMCs from several different somatic cells using a selection of protocols. As such, researchers have set out to delineate key signaling processes involved in triggering VSMC gene expression to grasp the extent of gene regulatory networks involved in phenotype commitment. This technology has also paved the way for investigations into diseases affecting VSMC behavior and function, which may be treatable once an identifiable culprit molecule or gene has been repaired. Moreover, induced pluripotent stem cell-derived VSMCs are also being considered for their use in tissue-engineered blood vessels as they may prove more beneficial than using autologous vessels. Finally, while several issues remains to be clarified before induced pluripotent stem cell-derived VSMCs can become used in regenerative medicine, they do offer both clinicians and researchers hope for both treating and understanding vascular disease. In this review, we aim to update the recent progress on VSMC generation from stem cells and the underlying molecular mechanisms of VSMC differentiation. We will also explore how the use of induced pluripotent stem cell-derived VSMCs has changed the game for regenerative medicine by offering new therapeutic avenues to clinicians, as well as providing researchers with a new platform for modeling of vascular disease. © 2017 American Heart Association, Inc.

  6. Evidence for network formation during the carbonization of coal from the combination of rheometry and {sup 1}H NMR techniques

    Energy Technology Data Exchange (ETDEWEB)

    Karen M. Steel; Miguel C. Diaz; John W. Patrick; Colin E. Snape [University of Nottingham, Nottingham (United Kingdom). Nottingham Fuel and Energy Centre, School of Chemical, Environmental and Mining Engineering

    2006-09-15

    High-temperature rheometry and {sup 1}H NMR have been combined to assess the microstructural changes taking place during carbonization of a number of different coals. A linear relationship exists between the logarithm of the material's complex viscosity ({eta}{sup {asterisk}}) and the fraction of hydrogen present in rigid structures ({phi}{sub rh}) for the resolidification region in which the material is liquid-like with small amounts of dispersed solid. The relationship is best characterized by the Arrhenius viscosity equation given by {eta}{sup {asterisk}} = {eta}{sub 0}{sup {asterisk}} exp(({eta}){phi}{sub rh}) where {eta}{sub 0}{sup {asterisk}} is the complex viscosity of the liquid medium and {eta} is the intrinsic viscosity of the resolidified material. Attempts to fit the Krieger-Dougherty suspension equation showed that the solid regions formed do not pack together like a normal suspension. Instead, it is more likely that cross-linking and cyclization reactions within the liquid medium give rise to a network structure of solid material and a characteristic gel point. The ratio of hydrogen present in rigid structures to that still present in liquid form at the gel point is approximately 2:3. The resolidified material was found to have a higher {eta} than the components of the coal that remained unsoftened, which suggests that while the unsoftened components have a fairly equant shape, the resolidified components have a much higher hydrodynamic volume. The resolidification process bears similarity with thermosetting polymer networks and the measurements taken for a blend of two coals follow a common two-component polymer blending rule. 35 refs., 13 figs., 4 tabs.

  7. Vascular tissue engineering by computer-aided laser micromachining.

    Science.gov (United States)

    Doraiswamy, Anand; Narayan, Roger J

    2010-04-28

    Many conventional technologies for fabricating tissue engineering scaffolds are not suitable for fabricating scaffolds with patient-specific attributes. For example, many conventional technologies for fabricating tissue engineering scaffolds do not provide control over overall scaffold geometry or over cell position within the scaffold. In this study, the use of computer-aided laser micromachining to create scaffolds for vascular tissue networks was investigated. Computer-aided laser micromachining was used to construct patterned surfaces in agarose or in silicon, which were used for differential adherence and growth of cells into vascular tissue networks. Concentric three-ring structures were fabricated on agarose hydrogel substrates, in which the inner ring contained human aortic endothelial cells, the middle ring contained HA587 human elastin and the outer ring contained human aortic vascular smooth muscle cells. Basement membrane matrix containing vascular endothelial growth factor and heparin was to promote proliferation of human aortic endothelial cells within the vascular tissue networks. Computer-aided laser micromachining provides a unique approach to fabricate small-diameter blood vessels for bypass surgery as well as other artificial tissues with complex geometries.

  8. Deleterious effects of tributyltin on porcine vascular stem cells physiology.

    Science.gov (United States)

    Bernardini, Chiara; Zannoni, Augusta; Bertocchi, Martina; Bianchi, Francesca; Salaroli, Roberta; Botelho, Giuliana; Bacci, Maria Laura; Ventrella, Vittoria; Forni, Monica

    2016-01-01

    The vascular functional and structural integrity is essential for the maintenance of the whole organism and it has been demonstrated that different types of vascular progenitor cells resident in the vessel wall play an important role in this process. The purpose of the present research was to observe the effect of tributyltin (TBT), a risk factor for vascular disorders, on porcine Aortic Vascular Precursor Cells (pAVPCs) in term of cytotoxicity, gene expression profile, functionality and differentiation potential. We have demonstrated that pAVPCs morphology deeply changed following TBT treatment. After 48h a cytotoxic effect has been detected and Annexin binding assay demonstrated that TBT induced apoptosis. The transcriptional profile of characteristic pericyte markers has been altered: TBT 10nM substantially induced alpha-SMA, while, TBT 500nM determined a significant reduction of all pericyte markers. IL-6 protein detected in the medium of pAVPCs treated with TBT at both doses studied and with a dose response. TBT has interfered with normal pAVPC functionality preventing their ability to support a capillary-like network. In addition TBT has determined an increase of pAVPC adipogenic differentiation. In conclusion in the present paper we have demonstrated that TBT alters the vascular stem cells in terms of structure, functionality and differentiating capability, therefore effects of TBT in blood should be deeply explored to understand the potential vascular risk associated with the alteration of vascular stem cell physiology. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Vascular Neurology Nurse Practitioner Provision of Telemedicine Consultations

    Directory of Open Access Journals (Sweden)

    Bart M. Demaerschalk

    2010-01-01

    Full Text Available Objective. The objective was to define and evaluate a role for the Vascular Neurology-Nurse Practitioner (VN-NP in the delivery of telemedicine consultations in partnership with a vascular neurologist. Methods. Prospective stroke alert patients at participating hospitals underwent a two-way audio video telemedicine consultation with a VN-NP at a remotely located stroke center in partnership with a vascular neurologist. Demographic information, National Institutes of Health Stroke Scale (NIHSS scores, diagnoses, CT contraindications to thrombolysis, thrombolysis eligibility, and time interval data were collected. The inter-rater agreement between VN-NP and vascular neurologist assessments was calculated. Results. Ten patients were evaluated. Four were determined to have ischemic stroke, one had a transient ischemic attack, two had intracerebral hemorrhages, and three were stroke mimics. Overall, three patients received thrombolysis. The inter-rater agreement between VN-NP and vascular neurologist assessments were excellent, ranging from 0.9 to 1.0. The duration of VN-NP consultation was 53.2±9.0 minutes, which included the vascular neurologist supervisory evaluation time of 12.0±9.6 minutes. Conclusion. This study illustrated that a stroke center VN-NP, in partnership with a vascular neurologist, could deliver timely telemedicine consultations, accurate diagnoses, and correct treatments in acute stroke patients who presented to remotely located rural emergency departments within a hub and spoke network. VN-NPs may fulfill the role of a telestroke provider.

  10. Vascular neurology nurse practitioner provision of telemedicine consultations.

    Science.gov (United States)

    Demaerschalk, Bart M; Kiernan, Terri-Ellen J; Investigators, Starr

    2010-01-01

    Objective. The objective was to define and evaluate a role for the Vascular Neurology-Nurse Practitioner (VN-NP) in the delivery of telemedicine consultations in partnership with a vascular neurologist. Methods. Prospective stroke alert patients at participating hospitals underwent a two-way audio video telemedicine consultation with a VN-NP at a remotely located stroke center in partnership with a vascular neurologist. Demographic information, National Institutes of Health Stroke Scale (NIHSS) scores, diagnoses, CT contraindications to thrombolysis, thrombolysis eligibility, and time interval data were collected. The inter-rater agreement between VN-NP and vascular neurologist assessments was calculated. Results. Ten patients were evaluated. Four were determined to have ischemic stroke, one had a transient ischemic attack, two had intracerebral hemorrhages, and three were stroke mimics. Overall, three patients received thrombolysis. The inter-rater agreement between VN-NP and vascular neurologist assessments were excellent, ranging from 0.9 to 1.0. The duration of VN-NP consultation was 53.2 +/- 9.0 minutes, which included the vascular neurologist supervisory evaluation time of 12.0 +/- 9.6 minutes. Conclusion. This study illustrated that a stroke center VN-NP, in partnership with a vascular neurologist, could deliver timely telemedicine consultations, accurate diagnoses, and correct treatments in acute stroke patients who presented to remotely located rural emergency departments within a hub and spoke network. VN-NPs may fulfill the role of a telestroke provider.

  11. The making of indigenous vascular prosthesis

    Directory of Open Access Journals (Sweden)

    Madathipat Unnikrishnan

    2016-01-01

    Full Text Available Background & objectives: Vascular illnesses are on the rise in India, due to increase in lifestyle diseases and demographic transition, requiring intervention to save life, organ or limbs using vascular prosthesis. The aim of this study was to develop indigenous large diameter vascular graft for treatment of patients with vascular pathologies. Methods: The South India Textile Research Association, at Coimbatore, Tamil Nadu, India, developed seamless woven polyester (Polyethylene terephthalate graft at its research wing. Further characterization and testing followed by clinical trials were conducted at Sree Chitra Tirunal Institute for Medical Sciences and Technology, Thiruvananthapuram, Kerala, India. Fifteen in vivo experiments were carried out in 1992-1994 in pigs as animal model. Controlled (phase I clinical trial in ten patients was performed along with control graft. Thereafter, phase II trial involved 22 patients who underwent multi-centre clinical trial in four centres across India. Results: Laboratory testing showed that polyester graft was non-toxic, non-leeching and non-haemolytic with preserved long-term quality, further confirming in pigs by implanting in thoracic aorta, comparable to control Dacron grafts. Perigraft incorporation and smooth neointima formation which are prime features of excellent healing characteristics, were noted at explantation at planned intervals. Subsequently in the phase I and II clinical trials, all patients had excellent recovery without mortality or device-related adverse events. Patients receiving the test graft were followed up for 10 and 5 years, respectively. Serial clinical, duplex scans and CT angiograms performed periodically confirmed excellent graft performance. Interpretation & conclusions: Indigenously developed Chitra vascular graft was comparable to commercially available Dacron graft, ready for clinical use at affordable cost to patients as against costly imported grafts.

  12. Albendazole inhibits endothelial cell migration, tube formation, vasopermeability, VEGF receptor-2 expression and suppresses retinal neovascularization in ROP model of angiogenesis

    Energy Technology Data Exchange (ETDEWEB)

    Pourgholami, Mohammad H., E-mail: mh.pourgholami@unsw.edu.au [University of New South Wales, Department of Surgery, St George Hospital (SESIAHS), Sydney (Australia); Khachigian, Levon M.; Fahmy, Roger G. [Centre for Vascular Research, The University of New South Wales, Department of Haematology, The Prince of Wales Hospital, Sydney (Australia); Badar, Samina; Wang, Lisa; Chu, Stephanie Wai Ling; Morris, David Lawson [University of New South Wales, Department of Surgery, St George Hospital (SESIAHS), Sydney (Australia)

    2010-07-09

    The angiogenic process begins with the cell proliferation and migration into the primary vascular network, and leads to vascularization of previously avascular tissues and organs as well to growth and remodeling of the initially homogeneous capillary plexus to form a new microcirculation. Additionally, an increase in microvascular permeability is a crucial step in angiogenesis. Vascular endothelial growth factor (VEGF) plays a central role in angiogenesis. We have previously reported that albendazole suppresses VEGF levels and inhibits malignant ascites formation, suggesting a possible effect on angiogenesis. This study was therefore designed to investigate the antiangiogenic effect of albendazole in non-cancerous models of angiogenesis. In vitro, treatment of human umbilical vein endothelial cells (HUVECs) with albendazole led to inhibition of tube formation, migration, permeability and down-regulation of the VEGF type 2 receptor (VEGFR-2). In vivo albendazole profoundly inhibited hyperoxia-induced retinal angiogenesis in mice. These results provide new insights into the antiangiogenic effects of albendazole.

  13. Albendazole inhibits endothelial cell migration, tube formation, vasopermeability, VEGF receptor-2 expression and suppresses retinal neovascularization in ROP model of angiogenesis

    International Nuclear Information System (INIS)

    Pourgholami, Mohammad H.; Khachigian, Levon M.; Fahmy, Roger G.; Badar, Samina; Wang, Lisa; Chu, Stephanie Wai Ling; Morris, David Lawson

    2010-01-01

    The angiogenic process begins with the cell proliferation and migration into the primary vascular network, and leads to vascularization of previously avascular tissues and organs as well to growth and remodeling of the initially homogeneous capillary plexus to form a new microcirculation. Additionally, an increase in microvascular permeability is a crucial step in angiogenesis. Vascular endothelial growth factor (VEGF) plays a central role in angiogenesis. We have previously reported that albendazole suppresses VEGF levels and inhibits malignant ascites formation, suggesting a possible effect on angiogenesis. This study was therefore designed to investigate the antiangiogenic effect of albendazole in non-cancerous models of angiogenesis. In vitro, treatment of human umbilical vein endothelial cells (HUVECs) with albendazole led to inhibition of tube formation, migration, permeability and down-regulation of the VEGF type 2 receptor (VEGFR-2). In vivo albendazole profoundly inhibited hyperoxia-induced retinal angiogenesis in mice. These results provide new insights into the antiangiogenic effects of albendazole.

  14. Mural cell associated VEGF is required for organotypic vessel formation.

    Directory of Open Access Journals (Sweden)

    Lasse Evensen

    Full Text Available BACKGROUND: Blood vessels comprise endothelial cells, mural cells (pericytes/vascular smooth muscle cells and basement membrane. During angiogenesis, mural cells are recruited to sprouting endothelial cells and define a stabilizing context, comprising cell-cell contacts, secreted growth factors and extracellular matrix components, that drives vessel maturation and resistance to anti-angiogenic therapeutics. METHODS AND FINDINGS: To better understand the basis for mural cell regulation of angiogenesis, we conducted high content imaging analysis on a microtiter plate format in vitro organotypic blood vessel system comprising primary human endothelial cells co-cultured with primary human mural cells. We show that endothelial cells co-cultured with mural cells undergo an extensive series of phenotypic changes reflective of several facets of blood vessel formation and maturation: Loss of cell proliferation, pathfinding-like cell migration, branching morphogenesis, basement membrane extracellular matrix protein deposition, lumen formation, anastamosis and development of a stabilized capillary-like network. This phenotypic sequence required endothelial-mural cell-cell contact, mural cell-derived VEGF and endothelial VEGFR2 signaling. Inhibiting formation of adherens junctions or basement membrane structures abrogated network formation. Notably, inhibition of mural cell VEGF expression could not be rescued by exogenous VEGF. CONCLUSIONS: These results suggest a unique role for mural cell-associated VEGF in driving vessel formation and maturation.

  15. Vascular remodeling and mineralocorticoids.

    Science.gov (United States)

    Weber, K T; Sun, Y; Campbell, S E; Slight, S H; Ganjam, V K

    1995-01-01

    Circulating mineralocorticoid hormones are so named because of their important homeostatic properties that regulate salt and water balance via their action on epithelial cells. A broader range of functions in nonclassic target cellular sites has been proposed for these steroids and includes their contribution to wound healing following injury. A chronic, inappropriate (relative to intravascular volume and dietary sodium intake) elevation of these circulating hormones evokes a wound healing response in the absence of tissue injury--a wound healing response gone awry. The adverse remodeling of vascularized tissues seen in association with chronic mineralocorticoid excess is the focus of this review.

  16. Convergent evolution of vascular optimization in kelp (Laminariales)

    DEFF Research Database (Denmark)

    Drobnitch, Sarah Tepler; Jensen, Kaare Hartvig; Prentice, Paige

    2015-01-01

    Terrestrial plants and mammals, although separated by a great evolutionary distance, have each arrived at a highly conserved body plan in which universal allometric scaling relationships govern the anatomy of vascular networks and key functional metabolic traits. The universality of allometric...... (Phaeophyceae) are one such group—as distantly related to plants as mammals, they have convergently evolved a plant-like body plan and a specialized phloem-like transport network. To evaluate possible scaling and optimization in the kelp vascular system, we developed a model of optimized transport anatomy...... and tested it with measurements of the giant kelp, Macrocystis pyrifera, which is among the largest and most successful of macroalgae. We also evaluated three classical allometric relationships pertaining to plant vascular tissues with a diverse sampling of kelp species. Macrocystis pyrifera displays strong...

  17. Self-expression and relationship formation in high relational mobility environments: A study of dual users of American and Japanese social networking sites.

    Science.gov (United States)

    Takemura, Kosuke; Suzuki, Satoko

    2017-06-01

    This study proposes that self-expression motivation, an aspect of independent/individualistic psychological tendencies, aids in the formation of social relationships when social relationships are open and mobile. In societies characterised by high relational mobility (e.g., North America), which creates market-like competition in social relationships, individuals must express their uniqueness and worthiness to form new social relationships. Self-expression motivation has a relatively weak effect on relationship formation in low relational mobility societies (e.g., Japan), where social relationships are generally predetermined. This hypothesis was examined and supported through a study on dual users of two social networking sites-Facebook and Mixi (the "Facebook of Japan"). As expected, relational mobility was higher on Facebook than on Mixi. Moreover, the association between self-expression motivation and the number of new friends met on Facebook/Mixi was more positive for Facebook than it was for Mixi. The social functionality of independent tendencies is then discussed. © 2015 International Union of Psychological Science.

  18. Low Immunogenic Endothelial Cells Maintain Morphological and Functional Properties Required for Vascular Tissue Engineering.

    Science.gov (United States)

    Lau, Skadi; Eicke, Dorothee; Carvalho Oliveira, Marco; Wiegmann, Bettina; Schrimpf, Claudia; Haverich, Axel; Blasczyk, Rainer; Wilhelmi, Mathias; Figueiredo, Constança; Böer, Ulrike

    2018-03-01

    The limited availability of native vessels suitable for the application as hemodialysis shunts or bypass material demands new strategies in cardiovascular surgery. Tissue-engineered vascular grafts containing autologous cells are considered ideal vessel replacements due to the low risk of rejection. However, endothelial cells (EC), which are central components of natural blood vessels, are difficult to obtain from elderly patients of poor health. Umbilical cord blood represents a promising alternative source for EC, but their allogeneic origin corresponds with the risk of rejection after allotransplantation. To reduce this risk, the human leukocyte antigen class I (HLA I) complex was stably silenced by lentiviral vector-mediated RNA interference (RNAi) in EC from peripheral blood and umbilical cord blood and vein. EC from all three sources were transduced by 93.1% ± 4.8% and effectively, HLA I-silenced by up to 67% compared to nontransduced (NT) cells or transduced with a nonspecific short hairpin RNA, respectively. Silenced EC remained capable to express characteristic endothelial surface markers such as CD31 and vascular endothelial cadherin important for constructing a tight barrier, as well as von Willebrand factor and endothelial nitric oxide synthase important for blood coagulation and vessel tone regulation. Moreover, HLA I-silenced EC were still able to align under unidirectional flow, to take up acetylated low-density lipoprotein, and to form capillary-like tube structures in three-dimensional fibrin gels similar to NT cells. In particular, addition of adipose tissue-derived mesenchymal stem cells significantly improved tube formation capability of HLA I-silenced EC toward long and widely branched vascular networks necessary for prevascularizing vascular grafts. Thus, silencing HLA I by RNAi represents a promising technique to reduce the immunogenic potential of EC from three different sources without interfering with EC-specific morphological and

  19. Templating Organosilicate Vitrification Using Unimolecular Self Organizing Polymers: Evolution of Morphology and Nanoporosity Development with Network Formation

    International Nuclear Information System (INIS)

    Kim, H.-C.

    2004-01-01

    Star-shaped polymers with a compatibilizing outer corona were dispersed into a thermosetting organosilicate matrix and used to create a nanoporous material. These environmentally responsive copolymers create nano-sized domains through a matrix-mediated collapse of the interior core of the core-corona polymeric structure. This approach relies on the outer corona of the star to compatibilize the insoluble core with the thermosetting resin and prevent aggregation such that these individual molecules template the crosslinking of the matrix and ultimately generate a single hole. The organic polymer was selectively thermalized leaving behind its latent image in the matrix with a pore size that reflected the size of the polymer molecule, and provided the expected reduction in dielectric constant. The morphology development as a function of arm number, molecular weight and volume fraction in mixtures with organosilicates as a function of cure/network conversion was investigated by SAXS, SANS, DMA, TEM and FE-SEM measurements. Amphiphilic star-shaped polymers of various block lengths and arm number, prepared by tandem controlled ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP) from dendritic initiators, were further tailored to facilitate contrast enhancement for various measurements by the incorporation of either ferrocenyl units or deuterated monomers. The pore sizes achieved by the star and dendrimer-like star macromolecular architectures range from ∼7 to 40nm, depending on the molecular weight and architecture

  20. Vascular anatomy of the pig kidney glomerulus: a qualitative study of corrosion casts.

    Science.gov (United States)

    Moore, B J; Holmes, K R; Xu, L X

    1992-09-01

    Pig kidney glomerular vascular anatomy was studied by scanning electron microscopy of vascular corrosion casts. A generalized vascular architecture is presented to describe the pig kidney glomerulus based upon the observation of 3,800 vascular cast glomeruli. The relative simplicity of the pig glomerular vascular architecture has allowed the characterization of different vascular segments more completely than has been possible in other mammals. Based upon relationships to the afferent arteriole, a nomenclature and definition of primary, secondary, tertiary and anastomotic vessels is proposed for the distributing vessels comprising the glomerular tuft. The existence and formation of a large central hemispheric vessel deep within the confines of a glomerular hemisphere is micrographically documented. Micrographic evidence is presented supporting the formation of the single efferent arteriole by the merging of two central hemispheric vessels within the confines of the glomerular tuft. Failure of the merging of these two vessels may result in multiple efferent arterioles.

  1. Interventional vascular radiology

    International Nuclear Information System (INIS)

    Yune, H.Y.

    1984-01-01

    The papers published during this past year in the area of interventional vascular radiology presented some useful modifications and further experiences both in the area of thromboembolic therapy and in dilation and thrombolysis, but no new techniques. As an introductory subject, an excellent monograph reviewing the current spectrum of pharmacoangiography was presented in Radiographics. Although the presented material is primarily in diagnostic application of various pharmacologic agents used today to facilitate demonstration of certain diagnostic criteria of various disease processes, both vasodilatory and vasoconstrictive reaction to these agents are widely used in various therapeutic vascular procedures. This monograph should be reviewed by every angiographer whether or not he or she performs interventional procedures, and it would be very convenient to have this table available in the angiography suite. In a related subject, Bookstein and co-workers have written an excellent review concerning pharmacologic manipulations of various blood coagulative parameters during angiography. Understanding the proper method of manipulation of the bloodclotting factors during angiography, and especially during interventional angiography, is extremely important. Particularly, the method of manipulating the coagulation with the use of heparin and protamine and modification of the platelet activity by using aspirin and dipyridamole are succinctly reviewed. The systemic and selective thrombolytic activities of streptokianse are also discussed

  2. Vascular dysfunction in preeclampsia.

    Science.gov (United States)

    Brennan, Lesley J; Morton, Jude S; Davidge, Sandra T

    2014-01-01

    Preeclampsia is a complex disorder which affects an estimated 5% of all pregnancies worldwide. It is diagnosed by hypertension in the presence of proteinuria after the 20th week of pregnancy and is a prominent cause of maternal morbidity and mortality. As delivery is currently the only known treatment, preeclampsia is also a leading cause of preterm delivery. Preeclampsia is associated with maternal vascular dysfunction, leading to serious cardiovascular risk both during and following pregnancy. Endothelial dysfunction, resulting in increased peripheral resistance, is an integral part of the maternal syndrome. While the cause of preeclampsia remains unknown, placental ischemia resulting from aberrant placentation is a fundamental characteristic of the disorder. Poor placentation is believed to stimulate the release of a number of factors including pro- and antiangiogenic factors and inflammatory activators into the maternal systemic circulation. These factors are critical mediators of vascular function and impact the endothelium in distinctive ways, including enhanced endothelial oxidative stress. The mechanisms of action and the consequences on the maternal vasculature will be discussed in this review. © 2013 John Wiley & Sons Ltd.

  3. Triassic North American paleodrainage networks and sediment dispersal of the Chinle Formation: A quantitative approach utilizing detrital zircons

    Science.gov (United States)

    Blum, M. D.; Umbarger, K.

    2017-12-01

    The Triassic Chinle Formation is a fluvial succession deposited in a backarc setting across the present-day Colorado Plateau of the southwestern United States. Existing studies have proposed various mechanisms responsible for the unique stratigraphic architecture and depositional sequences of the Chinle. However, these studies lack necessary age control to correlate stratigraphic patterns with contemporaneous mechanisms. This study will collect new samples for detrital zircon analysis, as well as upgrade existing samples (to n=300) from Dickinson and Gehrels (2008), to improve the resolution of Triassic sediment provenance from source-to-sink. The improved dataset allows appraisal of the multiple provenance terranes that contributed to the Chinle depositional system to delineate and reconstruct paleodrainage patterns. The additional samples will be collected systematically from the base of the Chinle, and vertically throughout the section to capture a regional story of how the continental scale drainage reorganized through time. U-Pb ages of detrital zircons will be utilized to provide quantitative fingerprinting information to constrain interpretations for the origin and transport history of the Chinle fluvial succession in time and space.

  4. Vascular Remodeling in Experimental Hypertension

    Directory of Open Access Journals (Sweden)

    Norma R. Risler

    2005-01-01

    Full Text Available The basic hemodynamic abnormality in hypertension is an increased peripheral resistance that is due mainly to a decreased vascular lumen derived from structural changes in the small arteries wall, named (as a whole vascular remodeling. The vascular wall is an active, flexible, and integrated organ made up of cellular (endothelial cells, smooth muscle cells, adventitia cells, and fibroblasts and noncellular (extracellular matrix components, which in a dynamic way change shape or number, or reorganize in response to physiological and pathological stimuli, maintaining the integrity of the vessel wall in physiological conditions or participating in the vascular changes in cardiovascular diseases such as hypertension. Research focused on new signaling pathways and molecules that can participate in the mechanisms of vascular remodeling has provided evidence showing that vascular structure is not only affected by blood pressure, but also by mechanisms that are independent of the increased pressure. This review will provide an overview of the evidence, explaining some of the pathophysiologic mechanisms participating in the development of the vascular remodeling, in experimental models of hypertension, with special reference to the findings in spontaneously hypertensive rats as a model of essential hypertension, and in fructose-fed rats as a model of secondary hypertension, in the context of the metabolic syndrome. The understanding of the mechanisms producing the vascular alterations will allow the development of novel pharmacological tools for vascular protection in hypertensive disease.

  5. Vector-based RNA interference against vascular endothelial growth factor-A significantly limits vascularization and growth of prostate cancer in vivo.

    Science.gov (United States)

    Wannenes, Francesca; Ciafré, Silvia Anna; Niola, Francesco; Frajese, Gaetano; Farace, Maria Giulia

    2005-12-01

    RNA interference technology is emerging as a very potent tool to obtain a cellular knockdown of a desired gene. In this work we used vector-based RNA interference to inhibit vascular endothelial growth factor (VEGF) expression in prostate cancer in vitro and in vivo. We demonstrated that transduction with a plasmid carrying a small interfering RNA targeting all isoforms of VEGF, dramatically impairs the expression of this growth factor in the human prostate cancer cell line PC3. As a consequence, PC3 cells loose their ability to induce one of the fundamental steps of angiogenesis, namely the formation of a tube-like network in vitro. Most importantly, our "therapeutic" vector is able to impair tumor growth rate and vascularization in vivo. We show that a single injection of naked plasmid in developing neoplastic mass significantly decreases microvessel density in an androgen-refractory prostate xenograft and is able to sustain a long-term slowing down of tumor growth. In conclusion, our results confirm the basic role of VEGF in the angiogenic development of prostate carcinoma, and suggest that the use of our vector-based RNA interference approach to inhibit angiogenesis could be an effective tool in view of future gene therapy applications for prostate cancer.

  6. Perturbing phosphoinositide homeostasis oppositely affects vascular differentiation in Arabidopsis thaliana roots

    NARCIS (Netherlands)

    Gujas, Bojan; Cruz, Tiago M D; Kastanaki, Elizabeth; Vermeer, Joop E M; Munnik, Teun; Rodriguez-Villalon, Antia

    2017-01-01

    The plant vascular network consists of specialized phloem and xylem elements that undergo two distinct morphogenetic developmental programs to become transport-functional units. Whereas vacuolar rupture is a determinant step in protoxylem differentiation, protophloem elements never form a big

  7. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    Science.gov (United States)

    Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

    2015-12-01

    The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements-including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth-were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light-tissue interactions and characterizing biophotonic system performance.

  8. Rapid prototyping of biomimetic vascular phantoms for hyperspectral reflectance imaging

    Science.gov (United States)

    Ghassemi, Pejhman; Wang, Jianting; Melchiorri, Anthony J.; Ramella-Roman, Jessica C.; Mathews, Scott A.; Coburn, James C.; Sorg, Brian S.; Chen, Yu; Joshua Pfefer, T.

    2015-01-01

    Abstract. The emerging technique of rapid prototyping with three-dimensional (3-D) printers provides a simple yet revolutionary method for fabricating objects with arbitrary geometry. The use of 3-D printing for generating morphologically biomimetic tissue phantoms based on medical images represents a potentially major advance over existing phantom approaches. Toward the goal of image-defined phantoms, we converted a segmented fundus image of the human retina into a matrix format and edited it to achieve a geometry suitable for printing. Phantoms with vessel-simulating channels were then printed using a photoreactive resin providing biologically relevant turbidity, as determined by spectrophotometry. The morphology of printed vessels was validated by x-ray microcomputed tomography. Channels were filled with hemoglobin (Hb) solutions undergoing desaturation, and phantoms were imaged with a near-infrared hyperspectral reflectance imaging system. Additionally, a phantom was printed incorporating two disjoint vascular networks at different depths, each filled with Hb solutions at different saturation levels. Light propagation effects noted during these measurements—including the influence of vessel density and depth on Hb concentration and saturation estimates, and the effect of wavelength on vessel visualization depth—were evaluated. Overall, our findings indicated that 3-D-printed biomimetic phantoms hold significant potential as realistic and practical tools for elucidating light–tissue interactions and characterizing biophotonic system performance. PMID:26662064

  9. Additive Manufacturing of Vascular Grafts and Vascularized Tissue Constructs.

    Science.gov (United States)

    Elomaa, Laura; Yang, Yunzhi Peter

    2017-10-01

    There is a great need for engineered vascular grafts among patients with cardiovascular diseases who are in need of bypass therapy and lack autologous healthy blood vessels. In addition, because of the severe worldwide shortage of organ donors, there is an increasing need for engineered vascularized tissue constructs as an alternative to organ transplants. Additive manufacturing (AM) offers great advantages and flexibility of fabrication of cell-laden, multimaterial, and anatomically shaped vascular grafts and vascularized tissue constructs. Various inkjet-, extrusion-, and photocrosslinking-based AM techniques have been applied to the fabrication of both self-standing vascular grafts and porous, vascularized tissue constructs. This review discusses the state-of-the-art research on the use of AM for vascular applications and the key criteria for biomaterials in the AM of both acellular and cellular constructs. We envision that new smart printing materials that can adapt to their environment and encourage rapid endothelialization and remodeling will be the key factor in the future for the successful AM of personalized and dynamic vascular tissue applications.

  10. Cardiac and vascular malformations

    International Nuclear Information System (INIS)

    Ley, S.; Ley-Zaporozhan, J.

    2015-01-01

    Malformations of the heart and great vessels show a high degree of variation. There are numerous variants and defects with only few clinical manifestations and are only detected by chance, such as a persistent left superior vena cava or a partial anomalous pulmonary venous connection. Other cardiovascular malformations are manifested directly after birth and need prompt mostly surgical interventions. At this point in time echocardiography is the diagnostic modality of choice for morphological and functional characterization of malformations. Additional imaging using computed tomography (CT) or magnetic resonance imaging (MRI) is only required in a minority of cases. If so, the small anatomical structures, the physiological tachycardia and tachypnea are a challenge for imaging modalities and strategies. This review article presents the most frequent vascular, cardiac and complex cardiovascular malformations independent of the first line diagnostic imaging modality. (orig.) [de

  11. Acceleration of vascularized bone tissue-engineered constructs in a large animal model combining intrinsic and extrinsic vascularization.

    Science.gov (United States)

    Weigand, Annika; Beier, Justus P; Hess, Andreas; Gerber, Thomas; Arkudas, Andreas; Horch, Raymund E; Boos, Anja M

    2015-05-01

    During the last decades, a range of excellent and promising strategies in Bone Tissue Engineering have been developed. However, the remaining major problem is the lack of vascularization. In this study, extrinsic and intrinsic vascularization strategies were combined for acceleration of vascularization. For optimal biomechanical stability of the defect site and simplifying future transition into clinical application, a primary stable and approved nanostructured bone substitute in clinically relevant size was used. An arteriovenous (AV) loop was microsurgically created in sheep and implanted, together with the bone substitute, in either perforated titanium chambers (intrinsic/extrinsic) for different time intervals of up to 18 weeks or isolated Teflon(®) chambers (intrinsic) for 18 weeks. Over time, magnetic resonance imaging and micro-computed tomography (CT) analyses illustrate the dense vascularization arising from the AV loop. The bone substitute was completely interspersed with newly formed tissue after 12 weeks of intrinsic/extrinsic vascularization and after 18 weeks of intrinsic/extrinsic and intrinsic vascularization. Successful matrix change from an inorganic to an organic scaffold could be demonstrated in vascularized areas with scanning electron microscopy and energy dispersive X-ray spectroscopy. Using the intrinsic vascularization method only, the degradation of the scaffold and osteoclastic activity was significantly lower after 18 weeks, compared with 12 and 18 weeks in the combined intrinsic-extrinsic model. Immunohistochemical staining revealed an increase in bone tissue formation over time, without a difference between intrinsic/extrinsic and intrinsic vascularization after 18 weeks. This study presents the combination of extrinsic and intrinsic vascularization strategies for the generation of an axially vascularized bone substitute in clinically relevant size using a large animal model. The additional extrinsic vascularization promotes tissue

  12. VEGF-A, cytoskeletal dynamics, and the pathological vascular phenotype

    International Nuclear Information System (INIS)

    Nagy, Janice A.; Senger, Donald R.

    2006-01-01

    Normal angiogenesis is a complex process involving the organization of proliferating and migrating endothelial cells (ECs) into a well-ordered and highly functional vascular network. In contrast, pathological angiogenesis, which is a conspicuous feature of tumor growth, ischemic diseases, and chronic inflammation, is characterized by vessels with aberrant angioarchitecture and compromised barrier function. Herein we review the subject of pathological angiogenesis, particularly that driven by vascular endothelial growth factor (VEGF-A), from a new perspective. We propose that the serious structural and functional anomalies associated with VEGF-A-elicited neovessels, reflect, at least in part, imbalances in the internal molecular cues that govern the ordered assembly of ECs into three dimensional vascular networks and preserve vessel barrier function. Adopting such a viewpoint widens the focus from solely on specific pro-angiogenic stimuli such as VEGF-A to include a key set of cytoskeletal regulatory molecules, the Rho GTPases, which are known to direct multiple aspects of vascular morphogenesis including EC motility, alignment, multi-cellular organization, as well as intercellular junction integrity. We offer this perspective to draw attention to the importance of endothelial cytoskeletal dynamics for proper neovascularization and to suggest new therapeutic strategies with the potential to improve the pathological vascular phenotype

  13. CIRSE Vascular Closure Device Registry

    NARCIS (Netherlands)

    Reekers, Jim A.; Müller-Hülsbeck, Stefan; Libicher, Martin; Atar, Eli; Trentmann, Jens; Goffette, Pierre; Borggrefe, Jan; Zeleňák, Kamil; Hooijboer, Pieter; Belli, Anna-Maria

    2011-01-01

    Vascular closure devices are routinely used after many vascular interventional radiology procedures. However, there have been no major multicenter studies to assess the safety and effectiveness of the routine use of closure devices in interventional radiology. The CIRSE registry of closure devices

  14. Diagnostic criteria for vascular dementia

    NARCIS (Netherlands)

    Scheltens, P.; Hijdra, A. H.

    1998-01-01

    The term vascular dementia implies the presence of a clinical syndrome (dementia) caused by, or at least assumed to be caused by, a specific disorder (cerebrovascular disease). In this review, the various sets of criteria used to define vascular dementia are outlined. The various sets of criteria

  15. The vascular secret of Klotho

    DEFF Research Database (Denmark)

    Lewin, Ewa; Olgaard, Klaus

    2015-01-01

    Klotho is an evolutionarily highly conserved protein related to longevity. Increasing evidence of a vascular protecting effect of the Klotho protein has emerged and might be important for future treatments of uremic vascular calcification. It is still disputed whether Klotho is locally expressed ...

  16. The impact of various scaffold components on vascularized bone constructs.

    Science.gov (United States)

    Eweida, Ahmad; Schulte, Matthias; Frisch, Oliver; Kneser, Ulrich; Harhaus, Leila

    2017-06-01

    Bone tissue engineering is gaining more interest in the field of craniofacial surgery where continuous efforts are being made to improve the outcomes via modulation of the scaffold components. In an in vitro three dimensional (3D) culture, the effect of bone morphogenic protein 2 (BMP2, 60 μg/ml) and the effect of different cell seeding densities (0.25, 0.5, and 1 × 104) of rat mesenchymal stem cells seeded on nanocrystalline hydroxyapatite in silica gel matrix (Nanobone ® ) on the cell viability and differentiation were studied. Alkaline phosphatase and viability assays were performed at day 7, day 14, and day 21 to assess the differentiation and the relative fraction of viable cells in the 3D cell cultures. In a subsequent in vivo study, we examined the effect of axial vascularization, the scaffold's particle size and the nature of the matrix (collagen type I vs. diluted fibrin) on vascularization and tissue generation in vascularized bone construct in rats. Regarding vascularization, we compared constructs vascularized randomly by extrinsic vascularization from the periphery of the implanted construct with others vascularized axially via an implanted arteriovenous loop (AVL). Regarding the particle size, we compared constructs having a scaffold particle size of 0.2 mm (powder) with other constructs having a particle size of 2 × 0.6 mm (granules). Regarding the matrix we compared constructs having a collagen matrix with others having a fibrin matrix. Various groups were compared regarding the amount of tissue generation, vascularization, and cellular proliferation. The initial seeding density had a temporary and minimal effect on the overall osteogenic differentiation of the cells. On the contrary, adding BMP2 in a concentration of 60 μg/ml over one week led to an overall enhanced osteogenic differentiation despite depressed cell viability. Axial vascularization was mandatory for efficient tissue formation and vascularization of the bone construct

  17. Pulmonary hypertension in children with congenital heart disease (PAH-CHD, PPHVD-CHD). Expert consensus statement on the diagnosis and treatment of paediatric pulmonary hypertension. The European Paediatric Pulmonary Vascular Disease Network, endorsed by ISHLT and DGPK.

    Science.gov (United States)

    Kozlik-Feldmann, Rainer; Hansmann, Georg; Bonnet, Damien; Schranz, Dietmar; Apitz, Christian; Michel-Behnke, Ina

    2016-05-01

    Pulmonary arterial hypertension associated with congenital heart disease (PAH-CHD) is a complex disease that presents with a broad spectrum of morphological and haemodynamic findings of varying severity. Recently, the aspect of paediatric pulmonary hypertensive vascular disease (PPHVD) has been introduced to expand the understanding of the full spectrum of pulmonary hypertension and increased pulmonary vascular resistance. Evaluation and treatment of PAH-CHD/PPHVD-CHD can be divided into in different topics. First, defining criteria for operability and initiation of advanced therapies preoperatively and postoperatively is an unresolved issue. Second, management of Eisenmenger syndrome is still an important question, with recent evidence on the severity of the disease and a more rapidly progressive course than previously described. Third, the Fontan circulation with no subpulmonary ventricle requires a distinct discussion, definition and classification since even a mild rise in pulmonary vascular resistance may lead to the so-called failing Fontan situation. Patients with CHD and single-ventricle physiology (Fontan/total cavopulmonary anastomosis) require a particularly stepwise and individualised approach. This consensus statement is on the current evidence for the most accurate evaluation and treatment of increased pulmonary artery pressure and resistance, as well as ventricular dysfunction, in children with congenital heart defects, and provides according practical recommendations. To optimise preoperative and postoperative management in patients with PAH-CHD, diagnostic and treatment algorithms are provided. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/

  18. FGF-dependent metabolic control of vascular development

    Science.gov (United States)

    Yu, Pengchun; Alves, Tiago C.; Fang, Jennifer S.; Xie, Yi; Zhu, Jie; Chen, Zehua; De Smet, Frederik; Zhang, Jiasheng; Jin, Suk-Won; Sun, Lele; Sun, Hongye; Kibbey, Richard G.; Hirschi, Karen K.; Hay, Nissim; Carmeliet, Peter; Chittenden, Thomas W.; Eichmann, Anne; Potente, Michael; Simons, Michael

    2017-01-01

    Blood and lymphatic vasculatures are intimately involved in tissue oxygenation and fluid homeostasis maintenance. Assembly of these vascular networks involves sprouting, migration and proliferation of endothelial cells. Recent studies have suggested that changes in cellular metabolism are of importance to these processes1. While much is known about vascular endothelial growth factor (VEGF)-dependent regulation of vascular development and metabolism2,3, little is understood about the role of fibroblast growth factors (FGFs) in this context4. Here we identify FGF receptor (FGFR) signaling as a critical regulator of vascular development. This is achieved by FGF-dependent control of c-MYC (MYC) expression that, in turn, regulates expression of the glycolytic enzyme hexokinase 2 (HK2). A decrease in HK2 levels in the absence of FGF signaling inputs results in decreased glycolysis leading to impaired endothelial cell proliferation and migration. Pan-endothelial- and lymphatic-specific Hk2 knockouts phenocopy blood and/or lymphatic vascular defects seen in Fgfr1/r3 double mutant mice while HK2 overexpression partially rescues the defects caused by suppression of FGF signaling. Thus, FGF-dependent regulation of endothelial glycolysis is a pivotal process in developmental and adult vascular growth and development. PMID:28467822

  19. Relational databases for rare disease study: application to vascular anomalies.

    Science.gov (United States)

    Perkins, Jonathan A; Coltrera, Marc D

    2008-01-01

    To design a relational database integrating clinical and basic science data needed for multidisciplinary treatment and research in the field of vascular anomalies. Based on data points agreed on by the American Society of Pediatric Otolaryngology (ASPO) Vascular Anomalies Task Force. The database design enables sharing of data subsets in a Health Insurance Portability and Accountability Act (HIPAA)-compliant manner for multisite collaborative trials. Vascular anomalies pose diagnostic and therapeutic challenges. Our understanding of these lesions and treatment improvement is limited by nonstandard terminology, severity assessment, and measures of treatment efficacy. The rarity of these lesions places a premium on coordinated studies among multiple participant sites. The relational database design is conceptually centered on subjects having 1 or more lesions. Each anomaly can be tracked individually along with their treatment outcomes. This design allows for differentiation between treatment responses and untreated lesions' natural course. The relational database design eliminates data entry redundancy and results in extremely flexible search and data export functionality. Vascular anomaly programs in the United States. A relational database correlating clinical findings and photographic, radiologic, histologic, and treatment data for vascular anomalies was created for stand-alone and multiuser networked systems. Proof of concept for independent site data gathering and HIPAA-compliant sharing of data subsets was demonstrated. The collaborative effort by the ASPO Vascular Anomalies Task Force to create the database helped define a common vascular anomaly data set. The resulting relational database software is a powerful tool to further the study of vascular anomalies and the development of evidence-based treatment innovation.

  20. Optimization of vascularization-­inducing hydrogel bioinks for 3D bioprinting

    Energy Technology Data Exchange (ETDEWEB)

    Lui, E. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States); Moya, Monica L. [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

    2016-09-12

    This study seeks to validate the reproducibility of previous bioprinting work at Lawrence Livermore National Laboratory (LLNL) on a new Aerotech motion controller system and to modify an existing bioink, fibrin, by adding varying percent volumes of hyaluronic acid (HA). Endothelial and fibroblast cells bioprinted in fibrin gels using the Aerotech system were confirmed to be more than 77 percent viable after one day, and all bioprinted samples retained sterility after one week of culture. To characterize cell behavior in fibrin with HA addition, static co-­culture gels with varying percent volumes of HA were cultured in vitro for one week. Resulting confocal microscope images showed increased cell network formation in all concentrations of HA compared to the control (no HA), and rheological tests mimicking static gel compositions displayed positive correlations between gelation time, gel stiffness (G’), and hyaluronic acid concentration. Although the current data is insufficient to quantitatively associate HA concentration with the level of cell vascularization, future work will aim to develop a targeted HA concentration in fibrin for maximum cell network formation, to optimize the printing process parameters for this new bioink composition, and to analyze cell viability in bioprinted fibrin-­HA structures.

  1. The vascular basement membrane as "soil" in brain metastasis.

    Directory of Open Access Journals (Sweden)

    W Shawn Carbonell

    2009-06-01

    Full Text Available Brain-specific homing and direct interactions with the neural substance are prominent hypotheses for brain metastasis formation and a modern manifestation of Paget's "seed and soil" concept. However, there is little direct evidence for this "neurotropic" growth in vivo. In contrast, many experimental studies have anecdotally noted the propensity of metastatic cells to grow along the exterior of pre-existing vessels of the CNS, a process termed vascular cooption. These observations suggest the "soil" for malignant cells in the CNS may well be vascular, rather than neuronal. We used in vivo experimental models of brain metastasis and analysis of human clinical specimens to test this hypothesis. Indeed, over 95% of early micrometastases examined demonstrated vascular cooption with little evidence for isolated neurotropic growth. This vessel interaction was adhesive in nature implicating the vascular basement membrane (VBM as the active substrate for tumor cell growth in the brain. Accordingly, VBM promoted adhesion and invasion of malignant cells and was sufficient for tumor growth prior to any evidence of angiogenesis. Blockade or loss of the beta1 integrin subunit in tumor cells prevented adhesion to VBM and attenuated metastasis establishment and growth in vivo. Our data establishes a new understanding of CNS metastasis formation and identifies the neurovasculature as the critical partner for such growth. Further, we have elucidated the mechanism of vascular cooption for the first time. These findings may help inform the design of effective molecular therapies for patients with fatal CNS malignancies.

  2. The Role of Wheat and Egg Constituents in the Formation of a Covalent and Non-covalent Protein Network in Fresh and Cooked Egg Noodles.

    Science.gov (United States)

    Lambrecht, Marlies A; Rombouts, Ine; Nivelle, Mieke A; Delcour, Jan A

    2017-01-01

    Noodles of constant protein content and flour-to-egg protein ratio were made with whole egg, egg white, or egg yolk. The optimal cooking time, water absorption, and cooking loss of salted whole egg noodles was respectively lower and higher than of egg white and egg yolk noodles. However, cooked whole egg noodles showed the best Kieffer-rig extensibility. Differences in noodle properties were linked to protein network formation. Disulfide bonds in whole egg noodles developed faster and to a larger extent during cooking than in egg yolk noodles but slower and to a lower extent than in egg white noodles. The balance between the rate of protein cross-linking and starch swelling determines cooked noodle properties. Ionic and hydrophobic protein interactions increase the optimum cooking time and total work in Kieffer-rig extensibility testing of fresh noodles. Hydrogen bonds and covalent cross-links are probably the main determinants of the extensibility of cooked noodles. © 2016 Institute of Food Technologists®.

  3. Delineating chalk sand distribution of Ekofisk formation using probabilistic neural network (PNN) and stepwise regression (SWR): Case study Danish North Sea field

    Science.gov (United States)

    Haris, A.; Nafian, M.; Riyanto, A.

    2017-07-01

    Danish North Sea Fields consist of several formations (Ekofisk, Tor, and Cromer Knoll) that was started from the age of Paleocene to Miocene. In this study, the integration of seismic and well log data set is carried out to determine the chalk sand distribution in the Danish North Sea field. The integration of seismic and well log data set is performed by using the seismic inversion analysis and seismic multi-attribute. The seismic inversion algorithm, which is used to derive acoustic impedance (AI), is model-based technique. The derived AI is then used as external attributes for the input of multi-attribute analysis. Moreover, the multi-attribute analysis is used to generate the linear and non-linear transformation of among well log properties. In the case of the linear model, selected transformation is conducted by weighting step-wise linear regression (SWR), while for the non-linear model is performed by using probabilistic neural networks (PNN). The estimated porosity, which is resulted by PNN shows better suited to the well log data compared with the results of SWR. This result can be understood since PNN perform non-linear regression so that the relationship between the attribute data and predicted log data can be optimized. The distribution of chalk sand has been successfully identified and characterized by porosity value ranging from 23% up to 30%.

  4. Data format translation routines

    International Nuclear Information System (INIS)

    Burris, R.D.

    1981-02-01

    To enable the effective connection of several dissimilar computers into a network, modification of the data being passed from one computer to another may become necessary. This document describes a package of routines which permit the translation of data in PDP-8 formats to PDP-11 or DECsystem-10 formats or from PDP-11 format to DECsystem-10 format. Additional routines are described which permit the effective use of the translation routines in the environment of the Fusion Energy Division (FED) network and the Elmo Bumpy Torus (EBT) data base

  5. Vascular disease in cocaine addiction.

    Science.gov (United States)

    Bachi, Keren; Mani, Venkatesh; Jeyachandran, Devi; Fayad, Zahi A; Goldstein, Rita Z; Alia-Klein, Nelly

    2017-07-01

    Cocaine, a powerful vasoconstrictor, induces immune responses including cytokine elevations. Chronic cocaine use is associated with functional brain impairments potentially mediated by vascular pathology. Although the Crack-Cocaine epidemic has declined, its vascular consequences are increasingly becoming evident among individuals with cocaine use disorder of that period, now aging. Paradoxically, during the period when prevention efforts could make a difference, this population receives psychosocial treatment at best. We review major postmortem and in vitro studies documenting cocaine-induced vascular toxicity. PubMed and Academic Search Complete were used with relevant terms. Findings consist of the major mechanisms of cocaine-induced vasoconstriction, endothelial dysfunction, and accelerated atherosclerosis, emphasizing acute, chronic, and secondary effects of cocaine. The etiology underlying cocaine's acute and chronic vascular effects is multifactorial, spanning hypertension, impaired homeostasis and platelet function, thrombosis, thromboembolism, and alterations in blood flow. Early detection of vascular disease in cocaine addiction by multimodality imaging is discussed. Treatment may be similar to indications in patients with traditional risk-factors, with few exceptions such as enhanced supportive care and use of benzodiazepines and phentolamine for sedation, and avoiding β-blockers. Given the vascular toxicity cocaine induces, further compounded by smoking and alcohol comorbidity, and interacting with aging of the crack generation, there is a public health imperative to identify pre-symptomatic markers of vascular impairments in cocaine addiction and employ preventive treatment to reduce silent disease progression. Copyright © 2017 Elsevier B.V. All rights reserved.

  6. [The future of vascular medicine].

    Science.gov (United States)

    Kroeger, K; Luther, B

    2014-10-01

    In the future vascular medicine will still have a great impact on health of people. It should be noted that the aging of the population does not lead to a dramatic increase in patient numbers, but will be associated with a changing spectrum of co-morbidities. In addition, vascular medical research has to include the intensive care special features of vascular patients, the involvement of vascular medicine in a holistic concept of fast-track surgery, a geriatric-oriented intensive monitoring and early geriatric rehabilitation. For the future acceptance of vascular medicine as a separate subject area under delimitation of cardiology and radiology is important. On the other hand, the subject is so complex and will become more complex in future specialisations that mixing of surgery and angiology is desirable, with the aim to preserve the vascular surgical knowledge and skills on par with the medical and interventional measures and further develop them. Only large, interdisciplinary guided vascular centres will be able to provide timely diagnosis and therapy, to deal with the growing multi-morbidity of the patient, to perform complex therapies even in an acute emergency and due to sufficient number of cases to present with well-trained and experienced teams. These requirements are mandatory to decrease patients' mortality step by step. Georg Thieme Verlag KG Stuttgart · New York.

  7. Contemporary vascular smartphone medical applications.

    Science.gov (United States)

    Carter, Thomas; O'Neill, Stephen; Johns, Neil; Brady, Richard R W

    2013-08-01

    Use of smartphones and medical mHealth applications (apps) within the clinical environment provides a potential means for delivering elements of vascular care. This article reviews the contemporary availability of apps specifically themed to major vascular diseases and the opportunities and concerns regarding their integration into practice. Smartphone apps relating to major vascular diseases were identified from the app stores for the 6 most popular smartphone platforms, including iPhone, Android, Blackberry, Nokia, Windows, and Samsung. Search terms included peripheral artery (arterial) disease, varicose veins, aortic aneurysm, carotid artery disease, amputation, ulcers, hyperhydrosis, thoracic outlet syndrome, vascular malformation, and lymphatic disorders. Forty-nine vascular-themed apps were identified. Sixteen (33%) were free of charge. Fifteen apps (31%) had customer satisfaction ratings, but only 3 (6%) had greater than 100. Only 13 apps (27%) had documented medical professional involvement in their design or content. The integration of apps into the delivery of care has the potential to benefit vascular health care workers and patients. However, high-quality apps designed by clinicians with vascular expertise are currently lacking and represent an area of concern in the mHealth market. Improvement in the quality and reliability of these apps will require the development of robust regulation. Copyright © 2013 Elsevier Inc. All rights reserved.

  8. Habit formation.

    Science.gov (United States)

    Smith, Kyle S; Graybiel, Ann M

    2016-03-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network.

  9. Habit formation

    Science.gov (United States)

    Smith, Kyle S.; Graybiel, Ann M.

    2016-01-01

    Habits, both good ones and bad ones, are pervasive in animal behavior. Important frameworks have been developed to understand habits through psychological and neurobiological studies. This work has given us a rich understanding of brain networks that promote habits, and has also helped us to understand what constitutes a habitual behavior as opposed to a behavior that is more flexible and prospective. Mounting evidence from studies using neural recording methods suggests that habit formation is not a simple process. We review this evidence and take the position that habits could be sculpted from multiple dissociable changes in neural activity. These changes occur across multiple brain regions and even within single brain regions. This strategy of classifying components of a habit based on different brain signals provides a potentially useful new way to conceive of disorders that involve overly fixed behaviors as arising from different potential dysfunctions within the brain's habit network. PMID:27069378

  10. Diabetes and Retinal Vascular Dysfunction

    Directory of Open Access Journals (Sweden)

    Eui Seok Shin

    2014-01-01

    Full Text Available Diabetes predominantly affects the microvascular circulation of the retina resulting in a range of structural changes unique to this tissue. These changes ultimately lead to altered permeability, hyperproliferation of endothelial cells and edema, and abnormal vascularization of the retina with resulting loss of vision. Enhanced production of inflammatory mediators and oxidative stress are primary insults with significant contribution to the pathogenesis of diabetic retinopathy (DR. We have determined the identity of the retinal vascular cells affected by hyperglycemia, and have delineated the cell autonomous impact of high glucose on function of these cells. We discuss some of the high glucose specific changes in retinal vascular cells and their contribution to retinal vascular dysfunction. This knowledge provides novel insight into the molecular and cellular defects contributing to the development and progression of diabetic retinopathy, and will aid in the development of innovative, as well as target specific therapeutic approaches for prevention and treatment of DR.

  11. Direct 3D bioprinting of perfusable vascular constructs using a blend bioink.

    Science.gov (United States)

    Jia, Weitao; Gungor-Ozkerim, P Selcan; Zhang, Yu Shrike; Yue, Kan; Zhu, Kai; Liu, Wanjun; Pi, Qingment; Byambaa, Batzaya; Dokmeci, Mehmet Remzi; Shin, Su Ryon; Khademhosseini, Ali

    2016-11-01

    Despite the significant technological advancement in tissue engineering, challenges still exist towards the development of complex and fully functional tissue constructs that mimic their natural counterparts. To address these challenges, bioprinting has emerged as an enabling technology to create highly organized three-dimensional (3D) vascular networks within engineered tissue constructs to promote the transport of oxygen, nutrients, and waste products, which can hardly be realized using conventional microfabrication techniques. Here, we report the development of a versatile 3D bioprinting strategy that employs biomimetic biomaterials and an advanced extrusion system to deposit perfusable vascular structures with highly ordered arrangements in a single-step process. In particular, a specially designed cell-responsive bioink consisting of gelatin methacryloyl (GelMA), sodium alginate, and 4-arm poly(ethylene glycol)-tetra-acrylate (PEGTA) was used in combination with a multilayered coaxial extrusion system to achieve direct 3D bioprinting. This blend bioink could be first ionically crosslinked by calcium ions followed by covalent photocrosslinking of GelMA and PEGTA to form stable constructs. The rheological properties of the bioink and the mechanical strengths of the resulting constructs were tuned by the introduction of PEGTA, which facilitated the precise deposition of complex multilayered 3D perfusable hollow tubes. This blend bioink also displayed favorable biological characteristics that supported the spreading and proliferation of encapsulated endothelial and stem cells in the bioprinted constructs, leading to the formation of biologically relevant, highly organized, perfusable vessels. These characteristics make this novel 3D bioprinting technique superior to conventional microfabrication or sacrificial templating approaches for fabrication of the perfusable vasculature. We envision that our advanced bioprinting technology and bioink formulation may also

  12. Vascular graft infections with Mycoplasma

    DEFF Research Database (Denmark)

    Levi-Mazloum, Niels Donald; Skov Jensen, J; Prag, J

    1995-01-01

    laboratory techniques, the percentage of culture-negative yet grossly infected vascular grafts seems to be increasing and is not adequately explained by the prior use of antibiotics. We have recently reported the first case of aortic graft infection with Mycoplasma. We therefore suggest the hypothesis...... that the large number of culture-negative yet grossly infected vascular grafts may be due to Mycoplasma infection not detected with conventional laboratory technique....

  13. Limb vascular function in women

    DEFF Research Database (Denmark)

    Hellsten, Ylva; Gliemann, Lasse

    2018-01-01

    Throughout life, women are subjected to both acute fluctuations in sex hormones, associated with the menstrual cycle, and chronic changes following the onset of menopause. Female sex hormones, and in particular estrogen, strongly influence cardiovascular function such as the regulation of vascular...... studies. Physical activity should be recommended for women of all ages, but the most essential timing for maintenance of vascular health may be from menopause and onwards....

  14. Facial vascular malformations in children

    International Nuclear Information System (INIS)

    Brunelle, F.O.; Lallemand, D.; Chaumont, P.; Teillac, D.; Manach, Y.

    1988-01-01

    The authors present their experience with conventional and digital angiography of vascular malformations of the head and neck in children. 22 hemangioendotheliomas, 8 venous angiomas, and 3 arteriovenous fistula were studied. 22 patients were embolised. DSA offers many advantages during the diagnostic as well as during the therapeutic phase of angiography. Embolization appears to have a major role in treatment of such vascular malformations. (orig.)

  15. Red de comunidades de aprendizaje, un espacio para la formación de formadores/ Learning network community, a space for the formation of teachers

    Directory of Open Access Journals (Sweden)

    Jorge Iván Ríos Rivera

    2007-01-01

    Full Text Available Cuando se habla de ambientes de aprendizaje se acude a un concepto muy necesitado para el desarrollo de la educación de hoy. Este, no se ha abordado, de manera detenida y profunda cuando se incorpora en los discursos de las TIC. Por ello se presenta en una de las materializaciones más promisorias del momento, llamada las comunidades de aprendizaje, además, pueden ser pensadas como espacios de formación de formadores dónde se propician muchas de las transformaciones requeridas en los docentes para la educación del nuevo mileno. El texto parte de la idea de formar a un maestro para contrarrestar el impacto de la escuela paralela a través de la creación de un “ecosistema comunicativo”, se relaciona la noción de ambiente de aprendizaje, en cada uno de sus componentes, Ambiente y aprendizaje, con el concepto de Redes de aprendizaje y comunidades de aprendizaje, para finalmente, ilustrar el modelo de red de comunidades de aprendizaje vivido desde la experiencia del proyecto REDES (MEN-UPB. When it is talked about learning environments, it is referred a much needed concept to the development of the nowadays education. This concept has not been treated in a deep and consciously way, when it has been incorporated to the speeches about the Information and communication technology (ICT. That is why is presented in one of the most hopefully materialization: the learning community, this could be also thought as a formation space for educators, a space where are favored many of the required transformation of the new millennium teachers. This article begins with the idea of educate a teacher, to counter the parallel school impact through the creation of a “communicative ecosystem”, then it is related the notion of learning environment, in each one of its components: environment and learning, with the concept of learning network and learning community. This article finishes with the illustration of the learning community network model

  16. Angiogenesis, Cancer, and Vascular Aging

    Directory of Open Access Journals (Sweden)

    Junji Moriya

    2017-10-01

    Full Text Available Several lines of evidence have revealed that the angiogenic response to ischemic injury declines with age, which might account for the increased morbidity and mortality of cardiovascular disease (CVD among the elderly. While impairment of angiogenesis with aging leads to delayed wound healing or exacerbation of atherosclerotic ischemic diseases, it also inhibits the progression of cancer. Age-related changes of angiogenesis have been considered to at least partly result from vascular aging or endothelial cell senescence. There is considerable evidence supporting the hypothesis that vascular cell senescence contributes to the pathogenesis of age-related CVD, suggesting that vascular aging could be an important therapeutic target. Since therapeutic angiogenesis is now regarded as a promising concept for patients with ischemic CVD, it has become even more important to understand the detailed molecular mechanisms underlying impairment of angiogenesis in older patients. To improve the usefulness of therapeutic angiogenesis, approaches are needed that can compensate for impaired angiogenic capacity in the elderly while not promoting the development or progression of malignancy. In this review, we briefly outline the mechanisms of angiogenesis and vascular aging, followed by a description of how vascular aging leads to impairment of angiogenesis. We also examine potential therapeutic approaches that could enhance angiogenesis and/or vascular function in the elderly, as well as discussing the possibility of anti-senescence therapy or reversal of endothelial cell senescence.

  17. Podoplanin increases the migration of human fibroblasts and affects the endothelial cell network formation: A possible role for cancer-associated fibroblasts in breast cancer progression.

    Directory of Open Access Journals (Sweden)

    Jaroslaw Suchanski

    Full Text Available In our previous studies we showed that in breast cancer podoplanin-positive cancer-associated fibroblasts correlated positively with tumor size, grade of malignancy, lymph node metastasis, lymphovascular invasion and poor patients' outcome. Therefore, the present study was undertaken to assess if podoplanin expressed by fibroblasts can affect malignancy-associated properties of breast cancer cells. Human fibroblastic cell lines (MSU1.1 and Hs 578Bst overexpressing podoplanin and control fibroblasts were co-cultured with breast cancer MDA-MB-231 and MCF7 cells and the impact of podoplanin expressed by fibroblasts on migration and invasiveness of breast cancer cells were studied in vitro. Migratory and invasive properties of breast cancer cells were not affected by the presence of podoplanin on the surface of fibroblasts. However, ectopic expression of podoplanin highly increases the migration of MSU1.1 and Hs 578Bst fibroblasts. The present study also revealed for the first time, that podoplanin expression affects the formation of pseudo tubes by endothelial cells. When human HSkMEC cells were co-cultured with podoplanin-rich fibroblasts the endothelial cell capillary-like network was characterized by significantly lower numbers of nodes and meshes than in co-cultures of endothelial cells with podoplanin-negative fibroblasts. The question remains as to how our experimental data can be correlated with previous clinical data showing an association between the presence of podoplanin-positive cancer-associated fibroblasts and progression of breast cancer. Therefore, we propose that expression of podoplanin by fibroblasts facilitates their movement into the tumor stroma, which creates a favorable microenvironment for tumor progression by increasing the number of cancer-associated fibroblasts, which produce numerous factors affecting proliferation, survival and invasion of cancer cells. In accordance with this, the present study revealed for the first

  18. Podoplanin increases the migration of human fibroblasts and affects the endothelial cell network formation: A possible role for cancer-associated fibroblasts in breast cancer progression.

    Science.gov (United States)

    Suchanski, Jaroslaw; Tejchman, Anna; Zacharski, Maciej; Piotrowska, Aleksandra; Grzegrzolka, Jedrzej; Chodaczek, Grzegorz; Nowinska, Katarzyna; Rys, Janusz; Dziegiel, Piotr; Kieda, Claudine; Ugorski, Maciej

    2017-01-01

    In our previous studies we showed that in breast cancer podoplanin-positive cancer-associated fibroblasts correlated positively with tumor size, grade of malignancy, lymph node metastasis, lymphovascular invasion and poor patients' outcome. Therefore, the present study was undertaken to assess if podoplanin expressed by fibroblasts can affect malignancy-associated properties of breast cancer cells. Human fibroblastic cell lines (MSU1.1 and Hs 578Bst) overexpressing podoplanin and control fibroblasts were co-cultured with breast cancer MDA-MB-231 and MCF7 cells and the impact of podoplanin expressed by fibroblasts on migration and invasiveness of breast cancer cells were studied in vitro. Migratory and invasive properties of breast cancer cells were not affected by the presence of podoplanin on the surface of fibroblasts. However, ectopic expression of podoplanin highly increases the migration of MSU1.1 and Hs 578Bst fibroblasts. The present study also revealed for the first time, that podoplanin expression affects the formation of pseudo tubes by endothelial cells. When human HSkMEC cells were co-cultured with podoplanin-rich fibroblasts the endothelial cell capillary-like network was characterized by significantly lower numbers of nodes and meshes than in co-cultures of endothelial cells with podoplanin-negative fibroblasts. The question remains as to how our experimental data can be correlated with previous clinical data showing an association between the presence of podoplanin-positive cancer-associated fibroblasts and progression of breast cancer. Therefore, we propose that expression of podoplanin by fibroblasts facilitates their movement into the tumor stroma, which creates a favorable microenvironment for tumor progression by increasing the number of cancer-associated fibroblasts, which produce numerous factors affecting proliferation, survival and invasion of cancer cells. In accordance with this, the present study revealed for the first time, that such

  19. Assessment of nitric oxide (NO) redox reactions contribution to nitrous oxide (N2 O) formation during nitrification using a multispecies metabolic network model.

    Science.gov (United States)

    Perez-Garcia, Octavio; Chandran, Kartik; Villas-Boas, Silas G; Singhal, Naresh

    2016-05-01

    Over the coming decades nitrous oxide (N2O) is expected to become a dominant greenhouse gas and atmospheric ozone depleting substance. In wastewater treatment systems, N2O is majorly produced by nitrifying microbes through biochemical reduction of nitrite (NO2(-)) and nitric oxide (NO). However it is unknown if the amount of N2O formed is affected by alternative NO redox reactions catalyzed by oxidative nitrite oxidoreductase (NirK), cytochromes (i.e., P460 [CytP460] and 554 [Cyt554 ]) and flavohemoglobins (Hmp) in ammonia- and nitrite-oxidizing bacteria (AOB and NOB, respectively). In this study, a mathematical model is developed to assess how N2O formation is affected by such alternative nitrogen redox transformations. The developed multispecies metabolic network model captures the nitrogen respiratory pathways inferred from genomes of eight AOB and NOB species. The performance of model variants, obtained as different combinations of active NO redox reactions, was assessed against nine experimental datasets for nitrifying cultures producing N2O at different concentration of electron donor and acceptor. Model predicted metabolic fluxes show that only variants that included NO oxidation to NO2(-) by CytP460 and Hmp in AOB gave statistically similar estimates to observed production rates of N2O, NO, NO2(-) and nitrate (NO3(-)), together with fractions of AOB and NOB species in biomass. Simulations showed that NO oxidation to NO2(-) decreased N2O formation by 60% without changing culture's NO2(-) production rate. Model variants including NO reduction to N2O by Cyt554 and cNor in NOB did not improve the accuracy of experimental datasets estimates, suggesting null N2O production by NOB during nitrification. Finally, the analysis shows that in nitrifying cultures transitioning from dissolved oxygen levels above 3.8 ± 0.38 to <1.5 ± 0.8 mg/L, NOB cells can oxidize the NO produced by AOB through reactions catalyzed by oxidative NirK. © 2015 Wiley Periodicals, Inc.

  20. BOLD Granger causality reflects vascular anatomy.